Eilat' Coral Reefs

Jacob Dafni Nowhere in the world do coral reefs exist in such proximity to a fast-growing city, to an oil port and to tourism-related development projects, and their mere preservation is a stimulating challenge. We believe that increased local awareness and utmost dedication of the community will ensure the survival of Eilat’s coral reefs against all odds. Dr. J. Dafni, a marine biologist who has been studying the northern Gulf of Aqaba for almost a half of a century, started his work there as a local guide for the Society for the Protection of Nature. He served initially as a warden in Eilat’s Coral Marine Reserve, and later, during his Master’s and PhD studies, explored the diversity and morphology of marine animals in polluted sites. In his scientific and educational career, as a teacher of marine studies and as a director of academic studies in a local college, he has never abandoned his faith that coexistence between urban development for the benefit of man and nature preservation is possible. Dr. Dafni’s previous book, “The Gulf of Eilat, from the Red Sea to the Red Line”, published in 2000 in Hebrew, is a comprehensive source book and an account of the natural and human history of the Gulf shared by four countries. The present book is an updated pictorial summary of the coral reef and adjacent habitats, within the boundaries of Israel’s coast. Cover photographs: The colorful diversity of Eilat’s coral reef fauna Photographers: I. Ben-tov, J. Dafni, M. Levin, D. Weinberg

Ye’ela Publishers 972-523-854981

To buy Dr. Jacob Dafni's book Press here

Eilat’s Coral Reefs

Eilat’s Coral Reefs

The last decade has brought new dangers to the coral world. Global warming, coral bleaching, over-exploitation, pollution and careless coastal development have affected almost all coral reefs and sites around the world. Eilat’s reefs have been spared the notorious bleaching effect, due to lower seawater temperatures, but human-related stresses affected the reefs of the Gulf, where scientists have recorded a notable decline of the diversity and degradation of coral reefs in the northern Gulf of Aqaba. Nonetheless, these reefs still show a high diversity of corals and reef organisms. The text and pictures included in this book are testimony to the rich and diverse fauna of Eilat’s coral reefs. Most of the photographs included in the book were taken there during the last 5 years.

Jacob Dafni

Photography: J. Dafni M. Levin & Divers of the “Tapuz” Diving Forum

Eilat’s Coral Reefs

© 2008 Jacob Dafni All rights Reserved By Ye’ela Publishers 2008 P.O.B. 14677, Eilat Israel 88580

‫אילת‬ ‫האלמוגים של‬ ‫שוניות‬ Eilat’s Coral Reefs ‫במבט אופטימי‬ Jacob Dafni, PhD Ben-Gurion University, Eilat Campus

Graphic Design: Lior Dafni Cover Design: Lior Dafni Printed and bound by El-Dan, Eilat

Photography: J. Dafni, M. Levin and Divers of the “Tapuz” Diving Forum

All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form, or by any means, electronics, mechanical, photocopying, recording or otherwise, without the .prior permission of the copyright holder

ISBN 978–965–91252–1–0 Printed in Israel 2008

Website: http://www.dafni.com/dafni-sites 1

Contents

1. Introduction

4

Preface Genesis

6 8

Tide and intertidal Coral reef The lagoon The open sea

10 12 16 18

Algae and seaweeds Sponges Cnidaria - Hydrozoa Jellyfishes

20 22 24 26

Coral main divisions Coral as a biotope Reef corals taxonomy Facts on corals Coral forms Hermatypic corals Ahermatypic corals Soft but not Soft Corals Soft Corals Gorgonians and Fan corals Sea Pens Organ-pipe Coral Sea Anemones

30 31 32 35 36-52 53 54 59 60-65 66 68 69 70

Worms Mollusca Shell-bearing snails Nude snails Bivalves Squid and Octopus Shrimp and Crabs Echinodermata Sea Stars Sea Urchins Sea Cucumbers Brittle Stars Feather Stars Tunicates Hemichordates, acorn worms

74 76 76 80 82 84 88 90 92 94 96 98 99 100 101

Coral fishes Sharks Skates and Rays Fishes as predators Eels and Moray eels Seahorse and relatives Pegasus Lionfishes Scorpionfishes and Stonefishes

103 104 106 107 108 110 112 113 114

2. Habitats of Eilat’s coast

3. Algae and lower animals

4. Corals, variety

5. Invertebrates

6. Reef fish & Vertebrates

2

10

20

28

74

102

Groupers Basslets or Goldies Butterflyfishes Angelfishes Damselfishes Wrasses Cleaning stations Parrotfishes Goatfishes and company Hawkfish Flounders and Soles Keeping a low profile Blennies Gobies Gobies and other small fishes Surgeonfishes Rabbitfishes Sea breams Nocturnal fishes Sweeper fishes Living in the current Triggerfishes and Filefishes Trunkfishes Porcupinefishes Pufferfishes Pearlfishes Anglerfishes On the sand and beneath Sea turtles Dolphins and Whales

116 117 118 120 122 124 126 128 130 131 132 133 134 136 137 138 140 141 142 144 145 146 148 149 150 151 152 153 154 155

High and low diversity Pollution types and effect Coral predation Artificial objects Species dynamics Coral nursery Artificial reefs Ship wrecks Underwater photography Diving sites Eilat Coral Nature Reserve Underwater Observatory Marine Park The “Dolphin Reef” Underwater restaurant Um-Rashrash Educational Coral Reserve Eilat’s coral reefs in the 21st century

157 158 159 160 164 165 166 169 170 171 172 174 176 177 178 180

7. Pollution and human effect

Endnotes Further Reading Glossary Indices Photo credits

156

182 183 184 186 190

3

About this Book

The aim of this book is to remind the reader of the presence of a living and active wildlife resource in the shallow water adjacent to the urban region of the City of Eilat. This natural resource suffered considerable damage during the last few decades, firstly because the main conservation efforts were concentrated on the 1.5 km stretch of the Coral Nature Reserve coast. Secondly, it was the common conviction of the local and national population that “there is nothing to see underwater in Eilat - everything is already gone”. In recent years, while investing special efforts to regulate the unprecedented large numbers of divers (who did not accept this doomsday prophecy), and to reclaim the neglected and dwindling reefs, it became evident that it is in fact possible to rehabilitate much of the damaged reefs and to establish a sustainable development program for the northern tip of the Gulf and its Eilat beaches. This includes enforcing of environmental protection regulations, and inserting artificial structures that will increase the shallow water capacity for fish and other marine organisms and of course benefit the divers. This book aims to advertise this blessed activity. The reader will find in this book a description of the habitats and their living organism inhabitants, and will see them as well as read about them. Various topics such as geological background, reef formation, tide, currents etc. will be mentioned briefly in everyman’s language, without burdening the reader with technical detail. Scientific terms marked in italics are explained in a short glossary at the book’s end. I am convinced that knowledge increases awareness, and public awareness is vital for the struggle to preserve the marine environment for our benefit and that of our children for decades to come. The tourist will find here a concise body of knowledge about the origin of the Red Sea, its geology, climate and tide regime. The diversity of coral colonies and their contribution to the reef is discussed, with emphasis on the organisms that reside amongst them in the reef and its environment, with abundant pictures, most of them taken in the last 5 years. Nevertheless, it is not a guide. You will find a reference list of books and guides for plants, invertebrates and fish at the end of the book. My previous book “Gulf of Eilat, from the Red Sea to the Red Line”, published in Hebrew in 2000 is a comprehensive account of the natural and human history of the Gulf and the northern Red Sea. Some of the included information has been incorporated into the present book. Identification of many organisms, especially invertebrates, is not always as simple as it is generally believed, since it must be done by experts for each and every taxonomical group, using subtle microscopic details. A special effort was done to establish the identity of most of the described species. I have also created an internet guide for the invertebrates of the Gulf of Aqaba (Eilat). It contains a collection of ca. 1200 species of corals, molluscs, sponges, worms, crustaceans and echinoderms. The reader is encouraged to use it: www.dafni.com/dafni-sites: Nevertheless, many scientific names are arbitrary, waiting for taxonomists’ decision*

Corals and Fishes in the coral reef

J. Dafni

* In uncertain scientific identifications you may often find the abbreviation cf., meaning “confer”, or “compare with”. The abbreviation sp. means that only the genus is known, and spp. means that several species may be included within this identification.

4

Coral reefs are the most diverse and beautiful of all marine habitats. Photo: J. Dafni, M. Levin

5

Preface

Sea and Life

Eilat is an ever-growing city with over 60,000 inhabitants. It was established in 1949, one mile west of the historical site of Biblical Eilat, in the Jordanian side of the border. During its first two decades, the town’s economy was based on copper mining in the surrounding desert, as well as on the development of a southern port for the state of Israel. An initiative to develop commercial fishing in the Gulf of Aqaba failed because of the limited level of organic productivity in the Gulf of Aqaba. In the mid 1960’s Eilat entered a new era as a tourist resort. Blessed by the relative warmth of the desert winter, the cool and blue waters of the Gulf, and of course the lavish and colorful coral reefs, Eilat has gained a worldwide reputation. A small stretch of shore was destined to be one of the first coral reef nature reserves in the world. Marine biological research and the Underwater Observatory Marine Park, established in 1975, brought millions of spectators closer to view and observe the seascape, and many scientists carried study of the coral realm. SCUBA diving and snorkeling are both well developed in Eilat and its neighboring towns. The last decade has brought new dangers to the entire coral world. Climatic and human activities unite to cause global warming, coral bleaching; over-exploitation of fish and other marine organisms, pollution and non-sustainable coastal development affected almost all coral reefs and sites around the world. In Bali, Indonesia, a world famous coral reef resource, only 6 percent of the reefs are now in healthy condition. The Eilat reefs have been spared the notorious bleaching effect, but a dispute has been raging for years regarding the possible deleterious effect of cage-based mariculture of fish near the northern shore of the Gulf, where many scientists have recorded a notable decline of the coral reef in the entire northern part of the Gulf of Aqaba. The appearance of coral reefs here is no less of a miracle. Favorable climate, clear water and other environmental factors turn the coral reefs into an underwater oasis in a nutrient-poor sea, justly named by marine ecologists a “blue desert“. Though, the content and pictures included here are testimony to the rich and diverse fauna and flora of the underwater environment of Eilat. Most of the pictures included in this book were taken during the last 5 years at Eilat reefs. Although we screened out many pictures showing damage and deterioration in the different habitats, the potential for healing is there, and measures combined with self-restraint of shore development entrepreneurs and divers will pay dividends in the future. Presently, measures taken by the Nature Reserve Authority, such as closure of certain protected areas and strict rules imposed on divers, are already showing results, but dangers still exist. We face the challenge of preserving this underwater bounty for the generations to come. We believe in the capacity of Eilat’s coral reefs to flourish. Against all odds, the coral reefs of Eilat should survive.

Life depends on water, and in the sea, water is quite common. A miraculous form of matter, water is the only compound found on Earth as solid (ice), liquid and gas (steam). Sea water is the cradle of life on Earth. Water absorbs the sun’s energy on summer days, warming the Earth; Water also radiates its heat to warm the air at night and throughout winter, and cools the air during daylight hours in the summer. Weather is all about water and air. Solar radiation causes evaporation, and in higher altitude the water liquefies, forming clouds that will be carried about by winds, and ultimately drop their charge as rain or snow. Eilat, due to its warmer air, gets very small quantities of rain and can be defined as a desert. In the warm climate of Eilat, rain and wind storms are very rare, and the climate is mild. Although in summer temperatures rise to 450C, in the low humidity the heat is less inconvenient than in humid regions. Once or twice a year, southern wave storms hit the northern part of the Gulf. They usually last several hours (picture). Billions of years ago in the sea, chemical molecules arranged themselves into a simple organism, which was able to exploit the earth’s mineral resources and reproduce: the first living creature. A further ‘invention’, photosynthesis, in plants, is the most important life-sustaining process in evolution: a unique molecule – chlorophyll – traps solar energy and turns carbon dioxide, a waste material, into glucose, the basic sugar that builds the living tissue of plants and is consumed by all animals along the food chain. Water takes an important role in this process.

Photo: J. Dafni

Southern storm waves hitting Eilat northern beach. Photo: M. Chen

6

Sea water is always on the move. Solar energy that warms the sea causes it to form currents that shift water masses from the warm tropics to the high latitudes, thus making human life there possible. Colder water currents move back to the tropics, sinking to the abyss. Due to topographic conditions – shallow sills in the southern entrance to the Red Sea – colder deep water does not enter it, and therefore its water temperature never drops below 200C (820F). Sea level is constantly changing. The gravitational pull of the sun and the moon causes sea level to rise in high tide, and drop down at low tide, six hours later. In Eilat, the tidal range is about 1 meter (3.3 feet) at most. Seasonal low tides cause the sea level to drop further and the coral reef top is exposed and many corals may die.

7

Genesis: How it came into being

All open seas are interconnected directly or through sea straits. Therefore a change in one sea affects other water bodies, either directly or indirectly. Eilat is situated at the remotest end of the Red Sea, in the northern Gulf of Aqaba (Gulf of Eilat). One glimpse at the map may reveal much of the structure and origin of this sea, and the processes that created its shape and nature. It is common knowledge that the Red Sea is part of the geological rift system formerly known as the “African-Syrian Rift”, a geological process that undoubtedly touched the early history of mankind that evolved in Africa and spread to other parts of the globe. We will discuss here in short these pre-historic events, and figure out how they affected the marine environment of our area. Africa and the Arabian Peninsula are shreds of a larger tectonic plate that tore and its pieces - African and Arabian tectonic plates drifted apart as much as 300 km, in the “Red Sea Rift”, for at least 35 million years. The rate of continental drift is too small to perceive visually, an annual 3-5 cm, but if multiplied by the millions of years that have elapsed, the width of the Red Sea is easily explained. The topography of the Arabian and African coasts and the obvious ‘fit’ - land heads against bays in the other side - is a convincing evidence to such tearing. Geologists believe that the Red Sea is the early stage, manifestation of a new ocean, which will reach its final size millions of years from now. Like most rifts, the Red Sea Rift has a smaller rift connected to it, which separates the small Sinai Plate from the Arabian Plate. It is called the “Dead Sea Rift”. Unlike

The Red Sea Rift, the Dead Sea Rift is a transform rift, meaning that land masses along this ‫סוואנות‬ ,‫יבשתי‬ ‫עמק בקע‬ ‫תחילה היה זה‬ .‫ומפרציו‬ ‫סוף‬-‫ים‬ ‫ ”שלבי‬fault. ‫ממחיש את‬ ‫האיור‬ rift do not‫שבו‬ split, they move horizontally alongside each other in a‫היווצרות‬ “strike-slip The Arabian ‫ אך‬,‫קדום‬ ‫סוף‬-‫ים‬ ‫ שיצרו‬and ,‫התיכון‬ ‫מכיוון הים‬ ‫הים‬-‫מי‬ ‫בהמשך‬ .‫וצומח טרופי‬ ‫ועולם‬ Plate moves northwards the Sinai plate is‫לבקע‬ shifted to the‫פרצו‬ south, in a movement that ‫חי‬ accounts ‫לים‬about ‫כיאות‬105 .‫טרופי‬ ‫מדרום‬ ‫נכנסו‬ ‫האוקיינוס‬ ‫הקשר הזה‬ ‫ניתק‬ ‫מאוחר יותר‬ for km ‫לים‬ over‫והפכוהו‬ the course of the last ‫ההודי‬ 20 million years.‫ומימי‬ The Dead Sea Rift extends all the ‫אל‬-‫באב‬ ‫במצר‬ ,‫לאוקיינוס‬ ‫מוצאו‬ .’‫ מ‬3,500-‫ל‬ ‫ מגיע‬Desert ‫ עומקו‬.‫מאד‬ ‫עמוק‬ ‫סוף‬-‫ים‬ ,‫גיאולוגי‬ ‫על בקע‬ way from the Gulf of Aqaba through the Arava and the Jordan Valley, forming sea‫שנוצר‬ floor ‫הוא “מיני‬ ‫ מפרץ‬.’‫ מ‬basins 130 ‫על‬of‫עולה‬ ‫מפתן‬ ‫ולו‬The ‫ק”מ‬attached 25-‫רוחבו כ‬ ,‫הוא צר‬ ,‫מנדב‬ deeps and ‫אילת‬ the terrestrial the ‫אינו‬ Dead‫שעומקו‬ Sea and,‫רדוד‬ other lakes. picture illustrates -‫לים‬process. ‫מפרץ אילת‬ ‫במוצא‬the ,‫טיראן‬ ‫עומקם של‬ .’‫ מ‬1860 ‫ק”מ‬ ‫ קטן‬time ‫שרוחבו‬ ,”‫סוף‬-‫ים‬ this Initially, Red ‫מצרי‬ Sea was a terrestrial rift ‫עומקו‬ valley,‫אך‬ like the20-‫מ‬ present African rift .‫הים‬ ‫ של‬the ‫אופיו‬ ‫חשיבות‬ ‫לתכונות אלה‬ ‫נראה כי‬ ‫ בהמשך‬connection .’‫ מ‬250-‫ כ‬,‫יחסית‬ ‫ רדוד‬,‫סוף‬ valley. Later sea‫בקביעת‬ invaded‫רבה‬ from the north, and finally the northern was closed and ‫הים‬Red ‫ מי‬Sea ‫בטמפרטורת‬ ‫שינוי‬ ‫לכך שיש‬ ‫גורם‬ ‫צפון‬-‫דרום‬ the became an extension of the Indian Ocean. ‫סוף ים סגור שכיוונו הכללי‬-‫היותו של ים‬ ‫ רק‬Sea ‫באילת‬ ‫ואילו‬ ,‫מעלות צלסיוס‬ 30-‫כ‬its‫סוף‬-‫ים‬ ‫בדרום‬ ‫המים‬ ‫טמפרטורות‬ .‫הממוצעות‬ .‫מעלות‬ The26Red basin is 3,500m deep, but opening to the Gulf of Aden is,‫בקיץ‬ narrow, 25km, ‫נמוכה‬ ‫טמפרטורת מים‬ ‫שכן‬deep. ,‫קריטית‬ ‫סוף‬-‫ים‬ ‫בצפון‬deep, )‫מעלות‬ ‫ חום‬and ‫ירידת‬shallow ‫בחורף‬ and shallow, only 130m The‫יותר‬ Gulf‫ומפרציו‬ of Aqaba – 1860m has20-‫(ל‬ also‫המים‬ a narrow .‫של ים סוף‬whereas ‫ לאורכו‬the ‫הים‬-‫מי‬ ‫ ניכרת‬,‫כן‬ ‫ כמו‬.‫אלמוגים‬ ‫שוניות‬ ‫מזו איננה‬ opening, Gulf‫במליחות‬ of Suez‫עלייה‬ is shallow throughout – only 80m ‫קיום‬ deep.‫מאפשרת‬ These properties .4.1% ‫לכדי‬ ‫ובמפרץ אילת היא‬ ‫בצפונו‬ – ‫בעוד שבדרום היא כמליחות מימי האוקיינוס‬ deeply affect‫מגיעה‬ the oceanographic nature of the,3.5% Red Sea. ,‫והמליחות‬ ‫הטמפרטורה‬ ,‫אלה‬a ‫לשני‬ .‫לאוקיינוס‬ ‫מים המחובר‬ ‫ביותר בגוף‬ ‫המליחות הגבוהה‬ ‫זוהי‬ ‫השפעה‬ Being an enclosed sea with south-north orientation explains the summer temperature ‫להתקיים‬from ‫מסוגל‬ ‫ימי‬-‫הטרופי‬ ‫והצומח‬ ‫כל החי‬ ‫ לא‬north, .‫ומפרציו‬ ‫סוף‬-‫בים‬ ‫תפוצת החי‬ ‫רבה‬ decline, 300C in the south, to 260C in the dropping as ‫והצומח‬ low as 200C in Eilat‫על‬ during ‫ומליחות‬in‫בטמפרטורות‬ the winter (nearing the lower limit for coral reef existence). .‫קיצוניות‬ A similar‫כה‬ gradient the salinity ‫ בירידה‬the ‫שהתבטאו‬ ‫תקופות‬ ‫כמה‬ ‫ הארץ‬record ‫על כדור‬for‫עברו‬ )‫האחרונות‬ ‫השנים‬ ‫(במיליון‬ ‫בעידן הרביעון‬ brings Gulf of,‫קרח‬ Aqaba next to a world oceanic seawater – 4.1%. Temperature and ‫להתכסות‬are,‫ואסיה‬ ‫אירופה‬which ,‫אמריקה‬ ‫לאזורים נרחבים‬ ‫וגרמו‬ ,‫בממוצע‬ ‫חום‬ 4-5-‫ כ‬the ‫של‬ salinity both factors limit‫בצפון‬ the distribution of Indian Ocean fauna and‫מעלות‬ flora along ‫תקופות‬ ‫בשיאן‬ ’‫ מ‬130for ‫בכדי‬ ‫את מפלס‬ ‫האוקיינוסים והוריד‬ ‫שנגרע‬in,‫קרח‬ ‫בשכבות‬ Red Sea,‫של‬and the cause the‫בהם‬ high‫המים‬ proportion of endemic species (up‫ממי‬ to 50% several fish ‫מלאה‬ ‫חלקית או‬ ‫גרמה לחסימה‬Period ‫שבפתחה‬ ‫הרדוד‬underwent ‫גובה המפתן‬ ‫סוף אל‬-‫בים‬ ‫מפלס המים‬ ‫ ירידת‬when .‫אלה‬ families). In the Quaternary the Earth several glacial periods (ice ages), ‫ גרמו‬,‫ בו‬global ‫המדבר הגובל‬ ‫ וחום‬dropped ‫מהקרינה‬by‫הנובעת‬ ‫וההתאדות‬ ‫חסימה‬seawater .‫ים לאגנו‬-‫מי‬ ‫כניסת‬ ‫של‬ average temperature several‫הרבה‬ degrees Celsius,,‫זו‬causing to cool and ice .‫שבו‬world’s ‫של החי‬temperate ‫או חלקית‬regions. ‫בהכחדה מלאה‬ ‫משבר‬ – ‫סוף‬-‫ים‬ ‫של‬surrounding ‫להתייבשות‬ to accumulate in the During ‫שהתבטא‬ the glacial periods the land ‫והצמחים‬ ‫החיים‬ ‫ בעלי‬more .‫ הים‬arid ‫לתחייתו של‬ ‫הביאה‬ 6000-‫לפני כ‬ ‫שחלה‬ ,‫האחרונה‬ ‫עליית‬ the Red Sea became than before, and,‫שנה‬ the meager supply of rain or river‫הים‬-‫פני‬ water to the ‫כששבו‬ ‫את הים‬ ‫ואכלסו‬ ‫ חזרו‬,‫סוף‬-‫ים‬ ‫למוצא‬ ,‫הערבי‬ ‫מחסה‬the‫ומצאו‬ ‫שחיו בו לפני‬ sea stopped, while evaporations lowered the‫הסמוך‬ seawater level‫בים‬ beyond 130m,‫המשבר‬ sill, connecting the ‫המיטביים לשרור‬ ‫התנאים‬ Red Sea with the Gulf of Aden. It is believed that the Red Sea became.‫בו‬ partially or totally isolated, ‫והתחדשו‬ ‫המשבר‬ ,‫שוניות קדומות‬ ‫ הן‬bottom. ‫של אילת‬In‫האלמוגים‬ ‫האלמוגים בחוף‬ possibly dried out‫בעת‬ and‫שמתו‬ salt accumulated in its the inter-glacial periods, ‫משוניות‬ between‫חלק‬ the ‫את‬ ‫שינתה‬seawater ‫סמוך לאילת‬ ‫במפלס מי‬ ’‫ מ‬130 ‫של‬with ‫שירידה‬ .‫מפלס הים‬ ‫בעקבות‬ glacials, level ‫המפרץ‬ rose again, and connection the ‫לזכור‬ ocean‫יש‬ resumed. It is‫עליית‬ assumed that ‫אז‬ ‫שנחשף‬ .‫יותר‬ ‫שנקבע מאוחר‬years ‫ הנוף‬ago, ‫רישומה על‬ ‫את‬dropped ‫והותירה‬130m ,‫תקופה‬ ‫באותה‬ ‫ מאד‬level. ‫מפת החוף‬ in the last ‫החוף‬ ice age, 12,000-15,000 sea level below present The ‫כיום‬ ‫שחלקם‬ ‫קניונים‬ ‫חרצו בו‬ ‫שנשפכו לתוך‬ ‫והנחלים‬ ‫והעמיק‬ more ‫מהווים‬ recent return of ,‫עמוקים‬ the sea, some 6,000 years‫המפרץ‬ ago, brought back most of the,‫מאד‬ animals and ‫התרחב‬ plants, .‫מבוקשים‬ ‫צלילה‬ ‫ימיים שהם‬-‫תת‬ ‫ נופים‬,‫מימית‬-‫התת‬ ‫מהטופוגרפיה‬ ‫חלק‬ which sheltered in the Gulf of Aden and‫יעדי‬ the Arabian Sea throughout the climatic crises, which is reflected by the high rate of endemism. It is also believed by some scientists that Eilat’s coral reefs are rejuvenated pre-Ice Age reefs. The latest Ice Age topography has been transformed into some beautiful underwater canyons and other attractive diving sites.

‫ים ומדבר נפגשים בראש מפרץ אילת‬ Desert and sea meet in the Gulf of Eilat (Aqaba)

Four stages in the creation of the Red Sea and its Gulfs. After S. Marco (1986).

8

Photo: J. Dafni

‫ דפני‬.‫ י‬:‫צילום‬

9

Habitats: Tides and intertidal

The phenomenon of cyclic oscillation of water level, the tide, is known in all marine and estuarine shores. The link between the water level and phases of the Moon and Sun has been known since ancient times. Observations show that high or low tide peaks lag by 52 minutes from one day to the next, and that highest vertical tidal extension appear in the beginning of the lunar month (as in the Hebrew calendar, which is based on the phases of the moon), and two weeks later, when both the Moon and Sun, are in a straight line relative to Earth and their gravitational forces combine.

Intertidal rocks and tide pools

The intertidal zone is your introduction to the marine realm. It is a “hybrid” between marine (in high tide) and terrestrial habitats (in low tide). For marine organisms the intertidal zone is a forbidding terrain. They face twice daily extremely different conditions on a twice-daily cycle being submerged at high tide, and totally exposed to strong solar radiation and dry air heat and high salinity several hours later when the water fall down. Furthermore, they have to withstand frequently strong wave conditions. On the other hand, the animals that adapted to inhabit the intertidal zone are less threatened by competition from other marine animals and usually develop larger populations. Generally, the intertidal zone has a much lower diversity of organisms than the submerged zones.

Animals in the intertidal beach rock and pools*: Chiton (Acanthopleura vaillantii), Barnacles (Tetraclita squamosa), preyed upon by Whelks (Thais hippocastanum), Common Limpet (Cellana eucosmia), Polished Nerita (Nerita orbignyana), Mangrove Prawn (Palaemon debilis), Blennid fish (Istiblennius edentulus). Photo: J. Dafni * Here, and throughout the book, the order of the pictures – if not stated otherwise – starts in the upper left, and continues in a clockwise direction.

10

Rocky Intertidal zone at Eilat: tide pools and beach-rock habitat. Small pictures: Shore Brittlestar (Ophiocoma scolopendrina), Shorecrab (Metopograpsus messor) and Periwinkles (Nodilittorina subnodosa) at low tide, climbing on top of each other to escape the scorching heat of the rock. Photo: J. Dafni

11

Habitats: Coral Reef

There are no creatures that better represent the shapes and colors of the underwater tropical habitat’s diversity than corals. The ‘living flowers’ roles extend far beyond mere beauty and splendor - they make up the underwater habitat itself. The evolution of corals started a half a billion years ago, and is still acting constantly. Coral individuals are called polyps. They reproduce both sexually, by emitting eggs and sperm into the water, and asexually, by division of polyps which remain clumped together to form colonies. The colonies, with their many identical polyps, may endure for thousands of years with no substantial change in their DNA content. Coral polyps, especially the Hexacorallians, form a communal or colonial solid limestone skeleton that remains intact after their death, and which should become, part of the unique sedimentary rock – the coral reef. If we only could go back in time and visit the Tethys Ocean 200 million years ago, we could meet similar underwater reefs, which limestone secretions comprises the mainframe of many of the present-day’s mountain ranges. The key to this evolutionary success is, no doubt, their cooperation with monocellular algae, the zooxanthellae, which entered their host’s tissues eons ago, and established with them symbiotic relationships that enables the corals to free themselves from complete dependence on external food sources, i.e. predation. On the contrary, many corals – through their algal partners – produce more food than they consume, the surplus of which feeds the surrounding fauna - worms, shrimps, mollusks, etc. Even if we ignore the corals’ cooperation with the algae their trapping of atmospheric greenhouse gas CO2 into their skeletons and ultimately into the reefs, we are still amazed by the richness and diversity of their species that makes up the core of the tropical “jungle” of the sea. The existence of a coral reef ecosystem in the northern Gulf of Aqaba is remarkable. Favorable climate, clear water and other environmental factors turn the coral reefs into an underwater oasis in the nutrient poor “blue desert”. The cooperation between corals and internally active algae enables them to flourish and sustain thousands of species of fish and invertebrate animals of great diversity. They exhibit an ideal answer to the challenge of living and prospering in an impoverished sea.

Zooxanthellae - algal symbionts of stony corals and other reef organisms. Right: coral colony and an individual polyp of the same species. Photo: H. Schuhmacher, J. Dafni

12

What is a coral - What is a reef?

1. A coral is a kind of small animal that reproduces asexually – by division or budding – to form large colonies of several to thousands of individual flower-like animals called polyps, which feed on small organisms called plankton. The polyps also reproduce sexually, by either internal or external fertilization. The juveniles called planules swim around for a while and settle on a solid substrate, starting new colonies. Many corals have a stony skeleton that grows gradually to immense size. 2. A reef is a geological formation produced continuously by many solid skeleton bearing organisms, whose dead skeletons later consolidate to form a solid framework that turns into a sedimentary rock. 3. Coral reef is a limestone structure made primarily by stony corals, consolidated by calcareous algae. A coral reef is usually three-dimensional, and has many fractures, crevices and caves that provide living space for thousands of invertebrate animals and fishes. It is considered the marine equivalent of the tropical jungle. 4. The Reef environment is colorful, teeming with life and activity. Predator-prey relationships, symbioses between plants and animals or between animal species of different origin and modes of life, all continuously interact in order to increase their survival and creation of the next generations.

Two coral types: Hickson’s Fancoral (Anella hicksoni), a gorgonian (above), and a stony coral (Montipora cf. stilosa) displaying its violet polyps. Photo: I. Ben-Tov

13

Coral Colony vs.

Gigantic coral colony of only one species: Boulder Coral (Porites columnaris). On the right, a large Organ pipe Sponge (Siphonochalina siphonella) protrudes from a crevice. Photo: J. Dafni

14

Coral Reef

A coral reef is made of many coral colonies of various species and accompanied by a diverse fish fauna. Photo: M. Levin

15

Habitats: the Lagoon

Lagoon inhabitants

Green meadow of Scaled Seagrass (Halophila stipulacea) and Oval Seagrass (H. ovalis) (inset). Photo: J. Dafni

Typical residents of the lagoon: Leather Anemone (Heteractis crispa) with a juvenile Clownfish. Photo: M. Levin

Long-spine Sea Urchins (Diadema setosum), Anemone carrier Hermit crab (Dardanus tinctor) and sand paste, emitted by an Acorn Worm (Ptychodera flava) (see page 100) hiding in the deep sand. Photo: J. Dafni

Sand dwelling Comb Sea Star (Astropecten polyacanthus) markings on the sand, crawling about and righting itself after accidental overturn. Photo: J. Dafni

Between the intertidal slope and the coral reefs of Eilat, stretches a narrow strip of shallow sand patches, strewn with rocks and occasional coral heads. This is the lagoon. At first glance, nothing attractive appears to exist there, and the snorkeler, swimmer or diver moves through it to reach the richest part – the coral reef flat. Yet, the lagoon has much more to offer. Many invertebrate animals live here, but their survival depends mainly on their ability to dig into the sand and hide from predators or in the case of predators, they have to camouflage themselves in order to approach their prey. Footprints and other markings in the sand disclose intensive activities there, mainly at night and early mornings. The lagoon floor is partly overgrown by sea grasses, several species of grass-like monocotyledon plants who invaded the shallow sandy areas and established there a lush cover of grass-like vegetation. Only two out of the 5 seagrass species known from the southern Gulf of Aqaba are found in Eilat shallows – Scaled Seagrass and the Oval Seagrass. The former is the main plant of the lagunar and reef front meadows, whereas the latter grows mainly around its margins. A large variety of fishes – mainly juveniles – and many invertebrates thrive among these plants’ leaves.

16

17

Habitats: the Open Sea

Open Sea life

The largest midwater top fish predator, a Great Barracuda (Sphyraena barracuda). Photo: B. Tamir

The open sea is a route, along which fish and invertebrate wander, with minimal contact with the shore. Some open sea fishes, such as the Whale Sharks swim along the shore, while reef fish prey upon the planktonic organisms like the delicate Comb Jellies (Unknown sp.). Photo: M. Levin, J. Dafni

The open sea is surprisingly close to the shore at Eilat. Because of the great depth of the Gulf (1860m), the outer slope of the reef and the external sand bottom flats descend steeply to deeper water. At a distance of 150m from the shore, the sea floor may already be 20m deep, and your full attention turns towards the clear blue water. What is there to see in these waters? Towards the shore the forereef slope towers upwards and along the sea floor itself several coral heads and reef knolls are teeming with thousands of small plankton-feeding fish. Fear of sharks? L arger sharks very seldom venture close to the shore. More frequently they visit the fish farms in the north shore, hoping to catch fish straying out of the nets. The only case of attack by a dangerous Mako Shark was 30 years ago, and since then there hasn’t been a single incident. All the same, be careful while swimming out to the open sea. Especially beware of speed boats. More common fish predator is the Barracuda. It is quite large and its silhouette blends with the coloration of the seawater, and it wanders close to the reef, lurking for straying reef fish. Apropos sharks, once or twice a year a lone Whale Shark, 10m or more in length swims all the way along the gulf to Eilat and can be spotted from the shore, or met in shallow water, attracting divers to touch or preferably, take pictures. It is a harmless plankton-feeding shark, and a welcomed visitor. The rarely seen Manta Ray (pages 106), another plankton-feeding cartilaginous fish, is also a giant, measuring over 6m across its ‘wings’. The only encounter I personally had with this creature at Eilat was as I was aboard a commercial aircraft about to land at the Eilat airport. Looking through the window, I saw it directly beneath, swimming majestically along the shore at about 300m from the beach.

18

19

Flora: Algae and Seaweeds

Plants are the foundation of all living systems. By means of photosynthesis - light energy and transforming it into organic matter – they economically sustain the entire food chain. The most common marine plants are algae, varying from microscopic single-celled algae to large, multicellular benthic algae called seaweeds. Except for the primitive prokaryotic (having no cell nucleus) blue-green algae, all algae are eukaryotic (i.e., having a cell nucleus). All algae also lack the vascular system, typical of land plants, as well as leaves, roots, flowers or seeds. They draw their water and minerals directly through their “skin”. Photosynthesis is carried out by organelles called chloroplasts. Since the chloroplasts’ shape and DNA structure is similar to that of the prokaryotic algae, it is believed that they evolved within the eukaryotic algae through a form of endosymbiosis. The algae are divided into divisions based on their pigments, Red algae, Brown algae, and Green algae etc. A group of one-celled eukaryotic algae, akin to the Red seaweed, are the freeswimming (planktonic) dinoflagellates and the related zooxanthellae. This last group’s role in the coral world cannot be exaggerated: They inhabit the body of most corals and many other marine organisms, carrying out their photosynthetic activity, providing their host with energy in the form of sugar and other carbon compounds. In the case of corals, they provide up to 90% of the host’s energy requirements, in return for protection and shelter, as well as their host’s respiration waste, the carbon dioxide, raw material for photosynthesis. Reef-building corals in particular depend on these endosymbionts both for nutrition and for calcium carbonate secretion. In the Gulf of Aqaba, both free-swimming algae and bottom dwelling seaweeds become abundant in the late winter and early spring, following the seasonal vertical mixing of nutrient rich water from deeper water, in the so-called Spring bloom.

A variety of Seaweeds

Codium arabicum, Dictyosphaeria cavernosa and Neomeris annulata – common benthic Green seaweeds in Eilat’s reefs. Photo: J. Dafni

Gracillaria sp., Asparagopsis taxiformis and Lithophyllum sp., benthic Red seaweeds in Eilat. Photo: J. Dafni

Turbinaria elatensis, Sargassum sp. and Padina gymnospora – common benthic Brown seaweeds in Eilat. Photo: J. Dafni Green algae (Chlorophyta): Enteromorpha clathrata covering the coral reef during the spring bloom, and Saw-tooth Alga (Caulerpa serrulata) from the lagoon. Photo: M. Levin, J. Dafni

20

21

Fauna: Sponges

More Sponges

Sponges: Fire Sponge (Negombata magnifica), with its specific predator, Pajama Slug (Chromodoris quadricolor), Red Keyhole Sponge (Mycale fistulifera) with parasitic polyps of a jellyfish Nausithoe sp. and Boring Sponge (Cliona vastifica) Photo: J. Dafni, M. Levin

More sponges. Grey Sponge (Crella cyathophora) a common sponge of the lagoon, found also on artificial structures and reefs, Tube Sponge (Siphonochalina sp.) and the Orange Sponge (Acanthella carteri). Photo: J. Dafni, M. Levin

Sponges (Porifera) are a diverse group of about 10,000 unique animal species, primarily inhabiting marine environments. In the past, they were mistaken for plants, because of their plantlike appearance, and their attachment to the rocks. Sponges are the oldest existing multicellular animals, and the simplest group, retaining a cellular level organization: similar cells do not combine to form tissue, and sponges have no body organs. In terms of gross morphology, sponges have no mouth or inner stomach, rather inner chambers interconnected by canals, open to the exterior. They have no muscle or nerve system, nor sensory organs. Feeding: seawater enters the body through tiny pores (ostia) in their outer surface, driven by the beating of whips (flagellae), located on specialized “collar cells” (choanocytes), that line the surfaces of chambers and the pore entrance. Food particles or micro-organisms are retained and ingested by the sponge cells. The flow of water through the canal system is unidirectional, exiting through larger openings (oscula). Sponges are either radially symmetrical or shapeless. Most sponges are supported by skeletons made up of the protein collagen and hard spicules, either calcareous or siliceous. The skeletal elements, collar cells and other cells are imbedded in a gelatinous matrix. The substance Spongin, in the form of flexible organic mesh, is present in most larger sponges. Reproduction is either sexual or asexual. Sponges are either male or female (some are hermaphroditic). In sexual reproduction, male gametes are released into the water and enter the pore systems of its neighbors. Spermatozoa are “captured” by collar cells, which then lose their collars and transform into specialized, amoeba-like cells that carry them to the eggs. In most sponges the fertilized egg develops into a blastula, which is released into the water. The larvae may settle directly and transform into adult sponges, or they may spend some time drifting as plankton. Asexual reproduction is by means of external or internal buds, which can survive unfavorable conditions, when the rest of the sponge dies. Most sponges are highly noxious, and only a few animals, mainly nudibranch slugs (page 80), manage to overcome their poison and feed on them. Sponges may have peculiar shapes, from a simple coating of the rock to well-defined tridimensional structures. They are usually scientifically identified by the shape of their spicules.

22

23

Cnidaria: Hydrozoa

Formerly known as Coelenterata, the Cnidaria are possibly the most important animals of the tropical marine environment. Including the classes Hydrozoa, Scyphozoa (jellyfish) and Anthozoa (corals and sea anemones), the Cnidaria are the most primitive multicellular animals. They appear both as colonies of sessile individuals called polyps, or in the form of a medusa. The class Hydrozoa is the most primitive cnidarian group, consisting of small solitary or colonial polyps that usually grow in subtidal areas or as marine fouling (organisms growing on submerged boats and artificial surface and piers). They show a large variety of shapes and life-cycle forms. Most hydrozoans have an alternate stage life-cycle (not unlike the caterpillarbutterfly relationship) – of a feeding polyp stage and an almost non-feeding modified stage, the medusa (hydromedusa), released to the water by the colony for sexual reproduction. Asexually, the polyps form – through budding – large colonies, that are either Leptothecata, having a solid, transparent cover (theca), into which the polyp’s tentacles retreat, or Anthoathecata, lacking this cover and therefore more flexible and less protected. Like all other Cnidaria they have stinging cells, cnidocytes, to paralyze their planktonic prey – shrimp, prawn or worm larvae, upon which the hydrozoans feed. At certain times they release to the water the hydromedusae, missioned to propagate the species by sexual reproduction. The spawned eggs and sperm develop into a planula, the typical cnidarian larva. It settles, after drifting a while in the open sea, on solid substrate, developing into a polyp. Several species are venomous to humans. The polyp stages of most hydrozoans are benthic, i.e. confined to permanent attachment to the substrate. The hydrozoan polyps are normally overlooked by divers. They are usually small, mostly transparent, and less conspicuous than the corals or sea-anemones. In most cases they are mistaken for algae or bryozoans – other fouling organisms. The hydromedusae are rather felt than seen: at certain seasons they swarm in the water, and swimmers are stung by their piercing sting. Tubularia is an anthoathecate hydrozoan solitary polyp, while the Hydractinia appears as nude polyps covering many sea snail shells, like dense hairs or felt. Another order of the Hydrozoa is the Siphonophora. These swimming animals superficially resemble jellyfish, but they differ in several aspects. Jellyfish are single medusa-like animals, whereas siphonophores are transparent colonies made of several polyps and medusae bound together, drifting in midwater, carried afloat by small gas-filled bubbles - floats. The long tentacles carry numerous stinging cells, and when they are seasonally abundant, their stinging touch is felt like whip lashes. Fortunately, our local species are less venomous than oceanic species

Hydrozoans: Tubularia sp., solitary polyps, and Eudendrium cf. ramosum a colonial anthoathecate hydrozoan common in the lagoon, found also on artificial structures and reefs. Photo: J. Dafni

24

Hydrozoa: Division Hydrocorallia

Here is a unique hydrozoan type that cannot be overlooked: the common Fire Coral. It is the only hermatypic (reef-building) hydrozoan genus. Its colonial calcareous skeleton adds to the stone-building effort of corals and other reef-builders. Like true corals, fire coral is heavily laden with symbiotic zooxanthellae that give away their photosynthate products to its host. Typically, a fire coral has polyps and medusae in its life-cycle, whereas Anthozoans – the true corals and sea anemones – have only one life form, the polyp. In addition, fire coral has three polyp types: mouthless dactylozoids that sting the prey, feeding polyps, called gastrozoids that ingest it, and the medusa-producing ampullae. As a rule, you can touch them (although it is not recommended) with your finger tips, but beware not to contact them with your bare chest, arm or legs. Hydromedusae are released in season, at which time they reproduce and die, leaving behind their planula larvae. Two species of fire coral are found in Eilat: Net Fire coral and Plate Fire coral. The aforementioned species, typical to the wave-beaten forereef is very sensitive to breakage by storms or humans – unwary divers and boat drivers.

Fire corals: Net Fire coral (Millepora dichotoma) form large colonies on the reef edge and Plate Fire coral (M. platyphylla), in the protected lagoon, the latter species is often infested by a Parasitic Barnacle (Wanella milleporae) and tube dwelling Christmas-Tree Worms (see page 47). Photo: J. Dafni

25

Cnidaria: Jellyfish

Jellyfishes belong to the Cnidarian class Scyphozoa. They are found mainly in open seas throughout the world. The body of an adult jellyfish is bell-shaped, made up of up to 98% water. The ‘bell,’ in addition to the basic layers of epidermis and gastrodermis, consists of a thick layer of compact jelly, termed mesogloea. In the lower part of the bell is the mouth, surrounded by longer or shorter tentacles. Each tentacle is equipped with many stinging cells, cnidocytes, which wound or kill their prey. As their shape is not hydrodynamic, jellyfishes swim slowly by pulsing their bodies and jetting water from beneath their bells. By definition, jellyfish are considered planktonic animals, passively drifting along, carried by the currents for long distances. They feed on fish and zooplankton paralyzed and caught by their tentacles. The mouth is used both to take in food and to expel waste. Like the hydrozoans, they practice alteration of generations, and most species start their life as planulae, developing into a polyp that divides or buds asexually, and later forms and expels platelike ephyrae which develop into adult medusae. So, contrary to hydrozoans, whose medusae are small and inconspicuous, Scyphozoans have tiny polyps and large medusae. Most jellyfish have a lifespan of few weeks; few live longer. Most pelagic jellyfish invade the Gulf from the Red Sea, form large swarms pushed northward by the tidal currents, ending their life either by being devoured by fish and turtles, or thrown ashore by the waves. None of the local common jellyfishes are dangerous to humans although now and then a migrating species may appear and inflict a painful sting. The Moon Jellyfish is the most common planktonic species, appearing in huge numbers in springtime, whereas another common species, the Upsidedown Jellyfish, belonging to the order Rhizostomae, does not have tentacles and is adapted to benthic life by turning its bell upside down and harboring large numbers of zooxanthellae closely packed in its mouth arms and many appendages around its mouth. Actually, in the adult Upside-down Jellyfish the mouth is closed and the animal totally depends on the algae’s sugar product as food.

Jellyfish: Moon Jellyfish (Aurelia aurita), and Upsidedown Jelly (Cassiopeia andromeda), at rest and turning to swim about. The dark appendages contain zooxanthellae. Photo: A. Colorni, J. Dafni

26

The Nettle Jellyfish (Chrysaora sp.), is an infrequent visitor in Eilat waters. be careful - It stings! Photo: O. Lederman

27

Cnidaria: Corals

Corals are the “trees” of the underwater tropical forest. All other organisms are in one way or another associated with them. A coral head is commonly perceived to be a single organism, but it actually consists of thousands of individual, genetically identical polyps, derived from asexual division or budding of a single individual polyp, that settled on hard substrate and its one-parent offspring remained attached to it. Coral species differ by their polyp size and shape, by their communal arrangement in large colonies and other related properties. The most important facts you should consider when thinking of them are: The shape of the growing colony depends on polyp type, available space, and environmental factors, like available light, currents and interaction with neighboring corals or other sedentary organisms. The same coral species may show different growth forms under different conditions. Coral classification is tricky – lots of technical terms are involved. To make identification simpler, we will try to arrange them in a convenient way, while conveying relevant information about them.

Coral Variety

2

Hard or soft?

Two main coral sub-classes exist: Hexacorallia which have polyps with six-fold radial symmetry, i.e., 6, 12, 18 or more tentacles. It includes the order of stony corals, Scleractinia, the “reefbuilding corals” (hermatypic). The hard coral polyps have a fixed colony shape, and the polyp resides in a 6-fold external solid calcareous cup, either solitary or in a larger colony (this subclass includes also the skeleton-less sea anemones and the black corals). In the other subclass, the Octocorallia (=Alcyonaria), known also as soft corals, polyps always have only 8 tentacles, fringed with secondary branches (pinnules), and an internal skeleton made of needle-like spicules. They are termed, with respect to their contribution to the reef, as “non-reef builders” (ahermatypic). Several other coral families are included among the Octocorallia, namely the gorgonians, the fan corals and the sea-pens. All coral polyps are predators, catching planktonic organisms and organic debris. They withdraw back into their skeletal or dermal surface in response to movement or disturbance, protruding later to feed. The polyps of stony corals usually extend their tentacles at night to capture the zooplankton that rises up from a depth of 200-400m. During daylight most of their tentacles retract, while their algal symbionts carry on their photosynthesis.

3

7 1 5

4 10

6

9 8

Hexacorallian polyps have 6, 12 or more tentacles, while Octocorallian polyps carry always 8 tentacles. Photo: J. Dafni

28

A typical coral reef view, displaying the variety of coral types cohabiting the same habitat: 1, Hydrocoral (Plate Fire coral), 2-6 Stony corals, 7-9 Soft corals and 10 an Corallimorpharian anemone. Photo: J. Dafni

29

Corals Division: Hexacorallia vs. Octocorallia

Similar but different: Above, Bird’s Nest Coral (Seriatopora hystrix), a branched stony coral (Hexacoral), and Fingered Soft-coral (Sinularia sp.) (Octocoral). Photo: J. Dafni

30

Corals as Habitat

Apart from being the main contributors to the coral reef framework, branched or pillar shaped corals offer living space for many invertebrates and fish. These inhabitants have to overcome the stinging of the polyps’ cnidocytes that provide their security against predators. It has been proven that these inhabitants pay back their host by enhancing water circulation at night – when the algae do not produce oxygen – as well as chasing away coral predators.

A branched Staghorn Coral (Acropora sp.) colony shelters Christmas tree worms (Spirobranchus giganteum). Below: Coral Crab (Trapezia tigrina) and Damselfishes (Chromis viridis). Photo: L. Dafni, I. Ben-Tov, J. Dafni

31

Variety of corals: Families

Variety of corals: Genera

Stony corals of the families Pocilloporidae, Poritidae, Mussidae, Pectinidae, Faviidae and Agariciidae. The diversity within the family Faviidae (arrow) will be shown on the next page. Photo: J. Dafni

Stony coral genera in the family Faviidae: Diploastrea, Echinopora, Erythrastrea, Goniastrea, Favia, and Platygyra. The variety within the genus Favia will be shown on the next page. Photo: D. Weinberg, J. Dafni

The variety of stony corals in Eilat’s reefs is something you do not see at first glance. Superficially, many corals look similar. Only after getting closer and paying attention to smaller details, does the immense diversity become clear. In the next few pages we will demonstrate this variety at the family level, at the genus level in one family, and among species within one genus, Favia (arrow).

32

The variety of stony corals in Eilat’s reefs can be perceived by looking at the various genera that make up the family Faviidae: no less than 12 different genera, with up to 15 species to each genus, totaling about 50 species. The six genera showed here exhibit well the variety of this family. For the variety in the genus Favia we will look in the next page (arrow).

33

Variety of corals: Species

Favia is a most variable genus. It shows a high similarity among its various species. We chose here to show six out of at least 15 species recorded from the Gulf of Aqaba, and Eilat’s reefs. Only a dedicated expert will be able to identify each and every species. Since I do not pretend to be a coral taxonomist, identification of these corals is arbitrary, open to comments and correction. The charm of the subtle differences in relative polyp size, coloration and sculptural design achieved through evolution cannot be denied.

Facts about Corals

After discussing and displaying some of the morphological variability of the stony corals, it might be helpful to present the main features by which the coral genera and species differ from each other. Obviously, it will be only in short paragraphs, and illustrated in the next few pages: • Polyps of stony corals are divided into six types by their corallite morphology (page 36). • Asexual reproduction by means of accretion of new polyps occurs either inside or outside the existing polyp’s tentacle circle (intra- or extra-tentacular budding) (page 36). • Since the grouping of species is basically according to corallite shape, sometimes branching and prostrate colonies may be grouped together as different species of the same genus (page 37). • The same principle can be observed within a single coral species – and even colony – which may show much different morphology in different parts of the colony or under different ecological conditions (pages 41, 49). • Stony corals are either solitary polyps or colonial. Some species, mainly those related to the mushroom coral family, of typically solitary polyps, are actually colonial, with only several polyp mouths opened along a longer furrow (page 38). • Even solitary corallites may result from a small colony. A mushroom coral (Fungia sp.) begins sometimes as small buds on a wounded polyp that grows and breaks off to lead a freeliving life style (page 39). • Mushroom Corals are not always detached from the substrate. The coral genus Cantharellus, although of the same family, is known to live permanently attached to the rock, sometimes in a vertical position (page 38). • The branched corals are probably the most important contributors to the spatial nature of the reef. Among their branches many invertebrates and fish find temporary shelter or permanent lodging. Many of these lodgers contribute to the welfare and security of their host-coral. Coral dwelling crabs chase away predatory sea stars, and damselfishes aerate the inter-branched space at night, which helps the coral to survive oxygen-poor conditions (pages 31). • Some massive coral colonies are no more than branched corals with their branches densely packed, each corallite riding on top of a ‘handle’-like branch. When the colony breaks, the individual branches are exposed (page 45). • Most colonies owe their gross morphology to the type of peripheral division or polyp accretion. Colonies in which all corallites divide equally will result with a ball shape, whereas those that divide or bud new polyps at their margin will produce plate or fan-like colonies. The same applies to branched colonies, such as plate-like colonies of Acropora cf. hyacinthus (pages 40, 51, 52). • Stony coral coloration normally results from the chlorophyll of symbiotic algae within the coral tissue. Under low light their number increase and the coral is darker. Chromo-proteins in the coral tissues add red, yellow or blue colors that mask the algal coloration (page 41). • Not all stony corals are reef builders. Unlike the reef-building hermatypic corals, corals that lack symbiotic algae, as well as soft corals with no calcareous skeleton, are termed ahermatypic, i.e. not reef builders (pages 54, 55). • Most stony corals are nocturnally active. During daylight their tentacles are retracted. A few species such as Goniopora and Alveopora have their polyps extended during the day (page 60)

Favia species from Eilat reefs: Favia cf. veroni, Favia stelligera, Favia cf. pallida, Favia laxa, Favia favus, and Favia cf. rotundata. Photo: J. Dafni

34

35

Stony corals: Corallite types

The shape of individual coral cups, the corallites, is primarily determined by their heredity as well as by their mode of asexual reproduction to form the colony. Stony corals are divided into six basic corallite types: cerioid, plocoid, phaceloid, meandroid, flabellate and hydnophorid. A further complication relates to the manner of asexual division of the polyps. It is either intratentacular or extratentacular. Intratentacular division, most typical among massive coral types, starts by deforming the round corallite into the shape of the number 8, with the appearance of a small partition inside the polyp’s tentacle circle that ultimately develops into a permanent dividing wall. A vertical section will show that they still retain this connection below the surface. In the extratentacular division, the colony produces buds outside the tentacular circle, attached to the adult polyp cup’s outer side.

Corals: Shapes of Corallites

Most of the corals’ skeletons show clearly during the day, when the polyps retract into the corallite cups. Their beauty is best appreciated when the bare skeleton is exposed. In this book we try however to concentrate on the morphology of the living tissue, just as we would not care to characterize our friends by their bare skeletons. The variability among species of the same genus is well demonstrated by the genus Echinopora. The next display (below) shows the delicate morphology and color of two related species.

Variability among the Echinopora genus: Echinopora fruticulosa, branched, Echinopora gemmacea, and Echinopora forskaliana, encrusting colonies. Photo: J. Dafni

Corallite types: cerioid, plocoid, phaceloid, hydnophorid, flabellate, and meandroid. Photo: J. Dafni, M. Levin, I. BenTov

Polyps’ division: Intratentacular division in Favia (left) and Extratentacular budding, in Echinopora polyps (arrows). Photo: J. Dafni

36

Corallites of exquisite beauty: Favia cf. pallida and Diploastrea heliopora. Photo: J. Dafni, D. Weinberg

37

Types of corals: Solitary

Most coral colonies start with one initial polyp that multiplies many times to form a colony. One has to be experienced to differentiate between a species that always consists of individual polyps, and an initial polyp of a new colony. Furthermore, some seemingly single polyps are in fact small colonies with inadequate borders between the polyps. The Fungiidae are typically free-living solitary polyps with some attached relatives (next page).

Solitary polyps: Cynarina lacrymalis, Lobophyllia cf. pachysepta, Trachyphyllia geoffroyi and Fungiid corals – Fungia fungites, Ctenactis echinata, and Cantharellus doederleini – the latter is an attached species of the mushroom coral family. Photo: R. Cohen, J. Dafni, M. Levin

38

Solitary corals: Mushroom corals

Mushroom Corals (family Fungiidae) are free-living individual stony corals. They form at youth a small sessile stalk that breaks off after a time and the polyps emerge to live individually. They live on the shallow sandy bottom, and even on a rock or reef surface. Mushroom corals, living on sand, are able to get rid of fine sediments by emitting mucus, upon which the sediment particles are carried away. Mushroom corals also have the capacity to rehabilitate from breakage. Further, from fractures and denuded areas small stalks (called anthocauli) develop into new polyps. Fungiids are known for their ability to move across the substrate.

Unusual mushroom corals: Typical Mushroom coral (Fungia fungites), serrated septa, short tentacles and a central mouth (see previous page), a mushroom anthocaulus emerging from underneath an adult corallite, Sharp mushroom coral (Ctenactis echinata) and Sandal coral (Herpolitha limax), a colony with several mouths. Photo: M. Levin, J. Dafni, A. Colorni

39

Growth forms: Branching

Staghorn coral Acropora is the most common circum-tropical coral genus. Acropora includes hundreds of species, most of them branched. Their typical feature is the single large polyp, or rather corallite cup, in the tip of each branch that grows faster than the other corallites along the branch, hence the scientific name (Acro=tip, Pora=hole). Although they engage in relations with zooxanthellae that provide them with food, they hunt plankton using their stinging cells. In the Pacific Ocean, Acropora often forms ‘forests’ of long and thin branches, highly vulnerable to breakage by storm waves. In the Eilat reef they usually mingle with other species. A notable exception are plate-shaped Acropora cf. hyacinthus that inhabit the lagoon areas closed to the public in the Eilat Nature Reserve (middle lower row, picture below).

More Branched Corals

Other branched corals are Stylophora, the most common coral in Eilat’s reefs. It has rounded blunt-topped branches with ca. 1 mm wide polyps. Coloration ranges from the usual creamyellow to pink and violet. Under shaded conditions it turns dark, due to excessive accumulation of zooxanthellae in its tissue. It is the first to settle in a new habitat, offering shelter to crabs and fish. The other genus, Pocillopora, less commonly named Cauliflower Coral, is a pink or violet dense bush with thicker branches that offer less access to epifauna. Another rare coral genus of the same family is Seriatopora. As implied by its scientific name the needle-hole size polyps are arranged in straight vertical lines. Colors range from cream to pink or blue. All three genera are opportunistic, rapidly growing corals (termed r-strategists), but poor competitors, short-lived, often replaced by longer lasting K-strategist corals.

Left: live Stylophora, Pocillopora, Seriatopora and Right: Seriatopora skeleton displaying the vertical arrangement of the polyps. Photo: J. Dafni

Environmental factors alter the shape and coloration of the coral colony. In the picture below, Stylophora, bright colored in an illuminated habitat compared with a much darker form growing in a shaded habitat (right). The effect of wave action upon two Pocillopora colonies: colony from an undisturbed back reef habitat (right) vs. a strongly flattened colony from a wave beaten reef front.

Acropora is the most common branched coral genus with over 15 species in Eilat’s coral reefs. They differ both in corallite size and form and of course in the colony shape*. Photo: J. Dafni, M. Levin * For an updated guide to the Eilat coral species: http://www.dafni.com/corals

40

Stylophora in illuminated vs. shaded habitat. Photo: J. Dafni

Pocillopora in a wave-beaten vs. protected habitat. Photo: J. Dafni

41

Growth forms: Massive

Massive or Hemisphere corals are globular or boulder-shaped coral colonies that grow only on their outer periphery. They are known to be slow-growing, and their polyps divide equally in all directions. Because of their very stable profiles and strong attachment to the substrate, they are more immune to strong wave action. Unlike the branched corals, the massive ones live longer; growing to very large sizes, and are better competitors (K-strategists). Massive corals produce annual density bands in their calcareous skeletons. The skeleton carries isotopic and geochemical tracers that can be used for age determination and reconstruction of the past sea surface temperatures (SST’s), and other seasonal climatic variables, such as precipitation and evaporation. From such evidence it was found that individual massive coral colonies may reach the age of several thousands years. Since it is known that Eilat’s reefs rehabilitated from the Ice Age sea level drop of over 100m about 6,000 years ago, it is probable that some of the oldest massive coral knolls’ age may date back to this event.

Massive coral colonies: Boulder Coral (Porites cf. lutea), Moon Coral (Favia stelligera) and a related coral (Goniastrea peresi). Photo: J. Dafni

42

Interaction between corals

Corals, like any other sedentary or territorial organism, compete to gain and protect their living space. Opportunistic branched corals succeed better in settlement on vacant rock. They find it difficult, however, to avoid being taken over by slower growing, sturdier massive corals. In interactions between corals of different species both rivals emit chemicals that affect their rivals’ growth and welfare, some of which are more effective than the others. Colonies of the same species are usually compatible, and in many cases merge.

Above: a massive Brain Coral (Platygyra daedalea) interacting with a Branched Table Coral (Acropora cf. hyacinthus). It is obvious who is winning. Bottom: Merging of three adjacent Brain Coral (Platygyra daedalea) colonies which retain their individual, somewhat different coloration. Photo: J. Dafni

43

Brain Corals

Colonies: Brain or branched?

Above: Folded partitions and deep grooves characterize the various species of Brain Corals (Platygyra spp.). Below: Huge Brain corals (same genus) dominate the lagoon view, Eilat Nature Reserve. Photo: J. Dafni

Lobed Coral (Lobophyllia corymbosa): entire colony and broken, exposing the individual polyp ‘handles’. Photo: J. Dafni

Brain corals are unique in the sense that neighboring polyps share a common groove, and the entire coral head is shaped like a folded human brain. The large colonies are often termed boulder corals.

44

Superficially, a Lobed Coral (Lobophyllia) looks like a brain coral, and is named so by many divers. Only when broken is the real nature of the colony revealed: each polyp rests upon a long dead ‘handle’ which is connected at its base to neighboring polyps (hence the Hebrew name – “torch coral”). This makes it very sensitive to breakage. A single broken polyp, glued to the substrate, will rehabilitate, and regenerate a new colony. Fragmentation under natural conditions of corals and regeneration is recognized as an alternative mode of asexual reproduction.

45

Growth forms: Encrusting

Encrusting juvenile colonies

Above: Two encrusting juvenile coral colonies: Staghorn Coral (Acropora sp.), Tubercle Coral (Montipora sp.), center and below: Galaxy Coral (Galaxea fascicularis) with a Coral Ghostfish (Solenostomus paradoxus). Photo: J. Dafni, M. Levin

Initial stages of Brain Coral (Platygyra sp.), Staghorn Coral (Acropora sp.), flat colony showing branch buds, Boulder Coral (Porites cf. mayeri), Platygyra daedalea, and juvenile stage of Plate Coral (Turbinaria sp.). Photo: J. Dafni

Encrusting corals cover the rock with little or no upward growth, but rather encompass the surface upon which they grow. They might differ in their polyp size or shape, but they never rise over the substrate. It is important to note that massive or even branched corals have an initial encrusting phase, in which they form their colony’s basis. Encrusting corals have the advantage over other types in wave-beaten reefs (next page).

46

Most massive or branched colonies have an initial encrusting stage, when the colony covers a given stretch, before starting to grow upwards. Sometimes, the entire nature of the coral is concealed by the prostrate appearance of the colony. It is more pronounced in variable shaped coral species (page 50).

47

Growth forms: Columnar

Growth forms: Foliaceous

Columns of Boulder Coral (Porites cf. columnaris). Photo: J. Dafni

Above: Plate Coral (Turbinaria sp.); Middle: Lettuce Coral (Pavona cactus). Below right: Elephant-ear Coral (Mycedium umbra), left: Cup Coral (Pachyseris speciosa). Photo: J. Dafni

Several massive corals show distinct “branching” of the large colony into pillars of variable height. In the picture below such a colony is shown. In the lower part of the pillars other species of corals more adapted to lower light intensities, and sponges, settled. Larger and medium sized fish seek shelter between the columns. The columnar shape is maintained by excessive growth of the upper, distal part.

48

Foliaceous corals are leaf-like colonies whose main growth increment is at its margins, thus forming thin plates that tend to fold and form curved surfaces. Most Foliaceous corals have their polyps on one (upper) side of the flat surface.

49

Growth forms: variable “Hybrids”

More “hybrids”

The Horn coral shows much different colony shapes in various parts of the colony. Below it appears as foliose or plate shaped, whereas above it appears as branches or pillars, making it difficult to identify by appearance only.

Two Lettuce corals (Pavona) also show mixed morphological characteristics. Maldive Lettuce Coral is partly flat foliaceous, partly columnar, while another Pavona sp. shows a buttressed foliaceous morphology.

Vertical variability in the shape of a Horn Coral (Hydnophora exesa) colony. Photo: J. Dafni

Two growth forms of the coral genus Pavona: P. maldivensis and Pavona sp. Photo: J. Dafni

50

51

Growth forms: Laminar

Hermatypic Corals

Laminar colonies of various coral species: Pavona cf. varians, Merulina cf. ampliata, and Leptoseris explanata. Photo: J. Dafni

Live coral reef: the hermatypic organisms provide the framework, the symbiotic algae harness light energy to produce food, fed by a multitude of fish and other reef inhabitants. The fish seen around the reef use the reef as base for plankton hunting in the incoming currents. Photo: M. Levin

Laminar corals are very thin horizontal leaf-like colonies. Corallites concentrate mainly in the upper surface. This characteristic is common to several families: Siderastreidae, Merulinidae, Agariciidae, Pectinidae etc.

52

All the stony corals shown above are hermatypic, participating in the construction of the coral reef, together with the calcareous products of other invertebrate organisms - mollusks, polychaetes and other skeleton-bearing animals. Calcium carbonate secreted by calcareous red algae consolidates them into a solid, geologically stable framework.

53

Ahermatypic Corals

Unlike the hermatypic corals that are the main contributors of calcareous material to the reef structure, ahermatypic corals do not contribute much to the coral reefs due to a lower rate of calcium carbonate deposition. In this definition are included hexacorals living in darker caves or in deep water, azooxanthellate (lacking the symbiotic algae that provide corals with their nutritious products), and octocorals whose main skeletal elements are calcite spicules imbedded in their soft tissue. The spicules disperse after the octocorals die, and enrich the sand with calcium carbonate. Many of the octocorals have zooxanthellae, but all the same their calcium carbonate contribution to the reef structure is negligible.

The ahermatypic hexacoral Sun Coral (Tubastrea coccinea) lives in darker undercuts and caves, and relies on plankton feeding. It is azooxanthellate, and its coloration is derived from pigments (inset: the same, with stretched out tentacles); other species of the same family, Dendrophyllidae, are Tubastrea micrantha (left) and two Cladopsammia spp. Photo: M. Levin, A. Colorni, I. Ben-tov

54

More Ahermatypic corals

Corals of one order in the Hexacorallia, the Zoanthidea, are ahermatypic: they lack stony framework, but unlike sea anemones, they form dense colonies that encrust stones and artificial surfaces with living cover. Zoanthids are highly toxic, protecting them from being eaten by animals.

Zoanthidea: Three Eilati ahermatypic Zoanthid corals. Photo: J. Dafni

55

Types of corals: Black Corals

More Black Corals

A full-size colony of Tree Black-Coral (Antipathes cf. dichotoma). Photo: M. Levin

Two species of Black-coral: Brown Barbed-Wire Coral (Cirripathes anguina) and Spiral Whip Coral (Cirripathes cf. spiralis). Photo: I. Ben-Tov, O. Lederman

Black coral is a term that defines the Antipatharia, another order of azooxanthellate Hexacorallia. They are either tree-like, elongated like a whip, or bent into a spiral. The living tissue may be colorful, but the flexible durable skeleton is black or dark brown. Two main types occur in Eilat’s deeper reef – Tree Black-corals and Barbed-wire black-corals. Their contribution to the reef structure is limited. Black Coral skeleton was used for the production of high quality polished black prayer beads in Yemen. It was also rumored to have been produced in old-time Aqaba.

56

Barbed wire is the first impression divers get from seeing it hanging or standing out from the coral reef towards the open water. It is hard, flexible and wiry.

57

Coral shapes: Microatolls

Microatolls are environmentally-induced bagel-like massive coral colonies in the lower intertidal or subtidal reef environments. Their unique shape indicates that vertical growth is constrained by frequent exposures to lowest spring tides, killing the uppermost polyps. As a result, microatolls usually grow laterally. The upper eroded surface of the colony is often densely grazed by sea urchins, limiting the settlement of algae and coral polyps. In Eilat microatolls are found mainly in the reef flat and in the inner lagoon. Microatolls found in deeper water may indicate lower sea level in the past. The name microatoll implies its resemblance to an atoll reef.

Shapes: Soft but no Soft coral

Most corals hunt at night. Only a few, like the Flower pot Coral, extend their polyps to feed during the day, and are therefore misidentified by many observers as soft corals. The picture below shows that they are definitely hexacorals, like all other stony corals. This becomes more obvious when examining their solid skeletons.

Flower pot Coral (Goniopora sp.) is an extraordinary example of a stony coral with long extended polyps during the day. Photo: J. Dafni

Above: Microatoll, a giant Brain Coral (Platygyra sp.) eroded in its middle. Note the exposed concentric growth-line pattern, the black-spine sea urchins, and the resettlement of other coral species – small massive, branching, and soft corals. Below: upper reef flat, where microatolls are usually formed. Photo: J. Dafni

58

Left and center: Goniopora usually has 24 tentacles, twice the number of its closest relative genus, Alveopora (right). Photo: J. Dafni, A. Colorni

59

Corals division: Soft corals

Pulsating Soft corals

Leather Coral (Sarcophyton sp.) shows the typical octocorallian eight-tentacle polyps emerging from its upper surface. The lower surface lacks polyps. Photo: J. Dafni

Pulsating soft corals, Heteroxenia (above) and Xenia (Ovabunda microspiculata). Photo: J. Dafni

Soft corals are octocorals which do not produce massive calcareous skeletons. Their rigidity is obtained by the internally-contained liquid pressure (hydro-skeleton). Unlike the stony corals that secrete an external rigid skeleton, to be consolidated with the hard bottom below, soft corals skeletons constitute of minute needles or spines called sclerites or spicules, imbedded inside their soft tissue. They are considered non reef-building corals. After they die their sclerites join the sand grains in the lagunar sand. Octocorals are divided into two main orders, Alcyonacea and Gorgonacea, and several small groups. The soft corals thrive in nutrient-rich waters or settle upon artificial structures, growing rapidly. Many alcyonarians harbor zooxanthellae that provide their energy requirements, and their colors are green-yellowish, the color of the symbiont. Some species overcome oxygen shortage by rhythmic pulsation of their tentacles. Gorgonians are mostly azooxanthellate, feeding on drifting food particles and plankton. Accordingly they prefer deeper water or darker caves, and their colors are brilliant.

60

Soft corals of the family Xeniidae are unique among corals because of their “pulsing“, pushing water away from the colony in a constant rhythmic motion. This action, once believed to help in catching food, is now thought to increase oxygen availability in low circulation environments.

61

Broccoli Soft corals

Colored Broccoli soft corals

Green Broccoli Coral (Litophyton arboreum), accompanied by a sponge and a Black coral, is commonly growing upon artificial metal structures, like the one attached to the underwater restaurant. Photo: J. Dafni

Red and Violet Broccoli Corals (Dendronephthya sp.), mingled with sponges, ascidians and other sedentary invertebrates at Moses Rock, Eilat Nature Reserve. Below: Close look at another broccoli coral, showing the red polyps and spicules in their transparent tissue. Photo: J. Dafni

It is hard to believe, but this green ‘broccoli’ is an animal, a coral. This shape is a common growth form shared by several soft coral species. Some, like the Green Broccoli Coral, are zooxanthellate, whereas other, or rather most soft corals are azooxanthellate, and of vivid colors (facing page). When in good shape they are swollen, maintaining vertical firmness. Under stress they become limp and hunched.

62

63

More Softies

The eight feather-like tentacles are typical of all octocorals, but in one coral, the Waving hand coral, the pinnules, or leaflets of each tentacle are large and wave in the current. A pale, almost colorless variation of the Broccoli coral is the Azooxanthellate Pallid broccoli coral. Independent of the light, it grows in darker deep water. Through the transparent ‘skin’ the calcareous spicules are clearly shown.

Pallid Broccoli Coral (Dendronephthya sp.) grows in deeper water; Waving Hand Coral (Anthelia sp) (inset) loses its zooxanthellae in aquarium. Photo: M. Levin, J. Dafni

64

Encrusting and Branching

Like stony corals, soft corals may show various growth forms: branching, encrusting, mushroomlike etc. They interact with each other and with stony corals to compete for living space. Chemical warfare plays an important role in this struggle.

Zooxanthllate Fingered Leather Coral (Cladiella sp.) spreading over the rreef surface competing with algae and corals for space. Tree-Coral (Paralemnalia sp.), typically showing long and dense soft digits. Photo: J. Dafni

65

Octocorals: Gorgonians

Fan Corals

Three Acabaria species, three colors: Splendid Acabaria (Acabaria cf. splendens), Red Sea Acabaria, (A. cf. erythraea) and Fair Acabaria (Acabaria cf. pulchra). Photo: M. Levin, J. Dafni

Hickson’s Fan Coral (Anella hicksoni) prefers deeper water (15-40m) where it reaches the size of 5 m. Inset: typical fish inhabitant, Longnose Hawkfish (Oxycirrhites typus). Photo: I. Ben-tov, B. Tamir

Gorgonians deserve more elaborate attention than the few words we can offer them here. This is because their habitat is well beyond the reach of the common visitor, or even diver. The smallest ones hide in deep and dark nooks and crannies, and the large ones, deepwater gorgonians, are easily ignored since their reddish colors turn black at depths of over 30 meters. The most common gorgonian genus in Eilat is Acabaria, with several species, mostly red, yellow or violet. The skeleton is flexible, but feeble. Polyps are usually white.

66

The largest gorgonian coral colony here is the fan coral; found mainly in the lower forereef, where they spread their erect and flat branches to filter out planktonic organisms from the currents. A beautiful fish species inhabiting this coral is a pointed-muzzle Longnose hawkfish (see also page 131) that finds shelter among the coral’s fine branches.

67

Organ Pipe Coral

Sea Pens

The Organ-pipe coral is an Octocoral, related to the soft corals, but is often referred to as a hard coral because of its solid skeleton. Its scientific name, Tubipora musica, refers to this coral’s colony shape formed from many vertical calcareous red tubes bound together by horizontal platforms: the entire skeleton resembles a pipe organ. Each tube is occupied by a single polyp that can retract into it, and the entire colony is covered by a thin and flexible horny cover. When its polyps are extended they entirely cover the skeletal structure. The pictures below show the red skeleton, the platforms, and the greenish polyp tentacles. It is zooxanthellate and reproduces asexually by sending extensions (stolons) and forming buds.

Sea pens are nocturnal colonial soft corals belonging to the order Pennatulacea. Unlike other Octocorallia, sea-pens’ polyps are specialized: one polyp, axial polyp, develops into a rigid, erect stalk (the rachis), with a bulbous peduncle, or “root“. Other polyps branch out from this central stalk, forming siphonozooids, water intake and feeding polyps (autozooids). The entire colony is in some species fortified by calcium carbonate spicules.

Organ Pipe Coral (Tubipora musica) overview: Colony and tentacles (above), with some polyps retracted, exposing the solid skeleton. Below, bare skeletons, in situ and cast ashore. Photo: J. Dafni

The common Sea Pen (Pteroides sp.): and an unknown relative species (below). They emerge at night, retracting into the sand by morning. Photo: M. Levin

68

69

Sea Anemones

Largest vs. Smallest Sea anemones

A variety of sea anemones: Sunray Anemone (Heteractis aurora) (above) and below, right to left: Leather Sea Anemone (H. crispa), usually accommodating juvenile clownfish; Commensal Anemone (Calliactis polypus), mostly associated with Hermit Crabs (see page 16) and Clownfish Anemone (Entacmea quadricolor), hosting the clownfish adults. Photo: J. Dafni, M. Levin

Adhesive Short-arm Anemone (Cryptodendrum adhesivum) - up to 40 cm, compared to the smallest Crab Carried Anemone (Triactis producta), 5 mm across (below right, arrows) held in the pincers of a small Anemone Carrier Crab (Lybia sp.). Left: a Squat Cleaner Shrimp (Thor amboinensis) is a commensal shrimp associated with large sea-anemones and sea cucumbers. Photo: L. Dafni, J. Dafni, O. Lederman

Related to the reef corals, sea-anemones are predatory animals differing from their stony coral relatives by (1) being predominantly solitary, although they may congregate in large aggregations, and (2) not producing calcareous skeletons. Sea-anemone sizes range from 5 mm to 40 cm. They reproduce either sexually or asexually, through division or budding. Large sea-anemones are inhabited by fish or shrimps, forming symbiotic relations with them.

70

By definition sea anemones are single polyps, and as with corals, sea anemones may be of varying size. The adhesive sea Anemone is probably the largest polyp among the Cnidaria. The smallest locally are the Crab-carried Anemones, associated with small crabs that carry them in their pincers (chelae) as weapons.

71

Tube Anemones

Coral anemones are a unique division – order Ceriantharia - of sand-dwelling solitary corals with anemone-shaped, elongated bodies and pointed ‘sole’ to enable burrowing in the sand. The body is covered by a cylindrical sheath and is usually hidden in sandy or muddy substrate. Usually only the tentacles are visible above the ground. The mouth, placed on a central disk, is surrounded by two crowns of tentacles: short labial tentacles and longer marginal tentacles. The external ones, variously colored, capture the prey and pass it to the internal (oral) tentacles that pass it to the mouth.

Wrapper Sea-anemone

These small Wrapper Sea-anemones, known also as Tiger anemones are always found enwrapped on branches of dead gorgonians or black corals. They are sometimes crowded on the gorgonian stalk to the point where no piece of the underlying coral skeleton is visible. Most of the anemones have uniform brown to orange color, while a few are whitish spotted with dark stripes. It is unknown whether they kill the coral or settle on the dead skeletons.

Ceriantharia: Tube Anemones (Cerianthus or Pachycerianthus sp.). The pictures were taken in the lagoon and in the sand flats among the reef knolls. Right, the membranous tubes, surrounded by a school of tiny Mysid Shrimps (Idiomysis tsurnamali), planktonic crustaceans that seek shelter among their tentacles. Photo: M. Levin, B. Tamir

Coral anemones

Corallimorpharia, or Disk anemones, are another group of sea anemone-like polyps with short or missing tentacles, and a flattish appearance. Their muscles are weak, and they cannot retract when threatened.

Corallimorpharian sea anemones: (right to left) unknown species; Actinodiscus nummiformis and Discosoma sp. Photo: J. Dafni

72

The Wrapper Anemone (Nemanthus annamensis) covering a dead sea whip and a fan coral showing both color patterns. Photo: I. Ben-Tov

73

Marine Worms

The term “worm” has been misused for many years as a common name for many kinds of animals, mostly drab and uninviting. Tropical marine worms, either Flatworms (phylum Platyhelminthes) or Bristleworms (phylum Annelida class Polychaeta) are diverse and beautiful, adorning the coral reef environment. The polychaete class is divided into two main groups – Errantia and Sedentaria. The errant worms are subterraneous, or hide inside reef crevices and seldom met by the casual diver, whereas the sedentary worms head carries long tentacles some of which convey to us their sheer beauty. They hide in soft organic or rigid calcareous tubes from which the tentacles emerge to catch plankton. Some species like the Eilat tubeworm, build a “reef” structure combining thousands of worm tubes into a magnificent flowerlike bounty. Another highlight is the Christmas-tree worm.

Flat Worms and Tube-dwelling Worms

One group of flatworms, the Polyclad Turbellaria, shows a high diversity of crawling and swimming beauties. Here are two chosen representatives.

Two worms, two life modes: swimming, Pseudobioceros sp. and crawling worm Pseudoceros. Colors are used for either for disguise or as warning coloration to deter predators. Photo: M. Levin An undetermined errant worm, found among coral debris in the lagoon. Photo: J. Dafni

Sedentary Polychaetes: Indian Tubeworm (Sabellastarte indica) and the variably colored Christmas-tree Worm (Spirobranchus giganteus). Photo: J. Dafni

74

More Sedentary polychaetes: The “reef-forming” of Eilat Tubeworm (Filogranella elatensis), firstly described in Eilat, common to many Indo-Pacific localities; the same, at closer look. Another reef tube worm, Striped Tubeworm (Sabellastarte cf. sanctijosephi.) and an unknown Sabellid (Sabella sp.). All radiate exquisite beauty. Photo: M. Levin, A. Colorni, J. Dafni

75

Mollusca: Gastropoda

Gastropods (snails) are the largest class in the phylum Mollusca, which includes three other common classes – Polyplacophora (chitons, see page 10), Bivalvia (clams) and Cephalopoda (squid and octopus) – well-represented in Eilat’s reefs. Over 800 gastropod species live here in a variety of habitats, from the intertidal to the deeper water. The gastropod shell is usually an external spiral or coiled shell, from which the snail body emerges and crawls on a flat “foot”. The shell is formed by calcium carbonate secreting glands in the mantle, adorned by color pigments that produce typical species-specific patterns. Commonly the word snail is restricted only to those species which have an external shell. Those without a shell or with only a very reduced or internal shell are termed slugs. Primitive gastropods, such as limpets, Top shells and Conchs are herbivores, scraping algae from the rock, whereas more advances species, like Frog shells, Helmet shells and Cones are carnivores. Cowries have mixed diets. Some predatory snails specialize on coral flesh (page 157). The mollusk shells are no less beautiful than the living animal. Yet the sea slugs, shell-less crawling and swimming gastropods, are splendid, showing astonishing colors and patterns (pages 80-81), which apparently serve as warning coloration to notify predators that they are distasteful or poisonous.

Turban Snail (Turbo radiatus) equipped with a calcareous operculum known as ‘cat’s eye’. Frog Snail (Tutufa rubeta), with a horny operculum, and a Top Shell (Trochus dentatus). Photo: J. Dafni

76

Samples of Gastropod diversity

The Spider conch uses its operculum as weapon. It is sharp, claw-like and the animal pushes it against intruders as well as using it to turn itself upside down. The cowry shell is always kept shining because it is completely enveloped by the two-fold mantle that covers it constantly with fresh enamel layers. The Striped engina is a modest small snail, one of many inhabiting the lower intertidal zone.

Spider Conch (Lambis truncata sebae) a vegetarian, and the Arabian Cowry (Mauritia arabica immanis) a scavenger – both are endemic Red Sea species, whereas Striped Engina (Engina mendicaria) is common throughout the entire IndoPacific. Photo: J. Dafni.

77

“Spider” strategy in Worm snails

Snail Reproductive behavior

Cluster of Large Tube Snails (Dendropoma maxima) totally covered by the mucous web and an Opercleless Tube Snail (Serpulorbis inopertus) (inset), with an emitted mucus strand. Photo: J. Dafni

A whelk (Nassa situla) female, and two Spindle Snails (Fusinus polygonoides) laying their egg in leathery. Moon Snail (Polinices mammilla) egg mass inside a “sand collar” (inset: bare shell) Photo: J. Dafni, M. Levin

Below, a unique group of specialized snails of the family Vermetidae is shown. Their calcareous tubes are permanently attached to the rock or merge into massive coral colonies. Their mode of feeding is similar to that of spiders. They produce silk-like mucous strands, and spread them in the vicinity of their tube aperture. Tiny plankton is entangled in the web. Every now and then the web is drawn in and the planktonic organisms and organic debris are ingested.

78

Snails reproduce internally – males and females meet and copulate. The eggs are liberated in egg strands, or in a variety of capsules, to protect the eggs from being eaten by fish and other browsers. Sand-dwelling snails produce a unique protecting device – a ‘sand collar’ - in which the entire egg mass is mixed with sand grains and glued together with mucous.

79

Opisthobranch snails - Slugs

In this subclass of Gastropods there is a tendency to lose the shell and adopt a bilateral symmetry, which shows best in the order Nudibranchia. As their scientific name implies these opisthobranchs replaced the fore gills (prosobranchs) with a ‘bouquet’ of modified gills around the anus. To compensate for the loss of the protective shell they are equipped with a poisonous mucous coating and vivid color patterns to advertise their being unpalatable. Some carnivorous slugs, of the suborder Aeolidina, prey on hydrozoans and store their cnidocytes secondarily in special club-like cnidosacs, in order to use them to defend themselves against predators.

Several nudibranchs, the most advanced opisthobranchs: Shield Slug (Phyllidia undula), the Aeolid Favorinus tsuruganus, and the Doriids, Ceratosoma magnificum, and Hypselodoris infucata. Photo: J. Dafni

80

Spanish Dancer

Spanish dancer Spanish dancer is the largest (up to 40 cm) nudibranch gastropod. It is known for its swimming behavior, gracefully flapping its mantle edges – in a manner similar to the dress lifting of Spanish flamenco dancers. The blood-red coloration is often adorned with a white margin to their mantle, and is considered a warning pattern, indicating to its enemies of having poisonous substances obtained from their food – sponges. They are hermaphroditic, and deposit their eggs within a gelatinous spiral strand.

Spanish Dancer, or “bloody six-gills” (Hexabranchus sanguineus) exhibited here, shows in the front are two modified tentacles (rhinophores), two oral flaps, and on the rear - a cluster of six branched gills. Spiral egg strand (inset). Photo: Y. Aharoni, A. Gur

81

Mollusca: Bivalvia

Bivalves are mollusks of the class Bivalvia. As their name implies, their shell consists of two valves or half-shells, hinged by an elastic ligament. Usually the two valves are similar and equal in size, but in some forms such as the oysters they attach to the substratum by one valve. Muscles run between the inner surfaces of the valves, enabling the shell to close rapidly and tightly. The mantle cavity hides the hatchet-like foot, used for burrowing in free-living species. Burrowing bivalves have two siphons, long or shorter tubes extending from the rear end, one for intake of oxygenated water and food, and another siphon for the outflow of wastes. The gills, within the mantle cavity, function in filter-feeding as well as in respiration. As water passes over the gills, tiny organic particles are strained out and carried to the mouth. Some bivalves attach themselves to surfaces by means of organic threads (called byssus), or by cementation. There are over 200 species of bivalves in the Gulf, among which you will find scallops, clams, oysters and mussels. Since the head is hidden, most bivalves have lost their eyes. Only a few, like the Coral clam shown here, have developed secondary eyes along the mantle edge.

Bivalvia: Giant clams

Giant clams, Tridacna maxima (above) and T. squamosa (center) are both symbiotic bivalves, harboring zooxanthellae that provide the clams with their produced food, mainly sugars. A 40 cm large clam is probably more than 20 years old. Protecting them from collectors and fishermen ensures their survival in the Eilat Coral Nature Reserve. Below Right: a Swimming clam (Lima sp.). Photo: J. Dafni, O. Lederman

Three bivalves: Coral Burying Clam (Pedum spondyloideum), displaying many eyes at the mantle’s margin, Sand buried Sand Pen Shell (Pinna muricata) and Egyptian Pearl Oyster (Pteria aegyptiaca). Photo: J. Dafni

82

83

Cephalopods: Cuttlefish and Octopus

The Cephalopods are the most advanced class of the phylum Mollusca, both in their swimming, crawling, “jet propulsion” and other behavioral aspects. They are characterized by bilateral symmetry, carrying a distinct head, and an attached mollusk foot which has been modified into 8-10 tentacles (hence the name cephalo=head, pod=foot). The class includes squids and cuttlefish which have an internal skeleton in the shape of a boat or flexible rod, whereas members of the octopus class lack any kind of hard skeleton. Cephalopods are regarded as the most intelligent of the invertebrates and have well-developed senses. They have special skin cells called chromatophores that change color and are used for communication and camouflage. All cepahlopods spurt black ink to ward off predators and as “smoke screen”. Octopuses have 8 arms, while cuttlefish and squid have an extra pair of longer tentacles, with which they grasp their prey, and a powerful sharp beak.

Cephalopods: Octopuses

The octopus has no internal skeleton or outer shell, which enables it to squeeze through narrow spaces. It is very intelligent, and preys upon fish and invertebrates. Like other cephalopods, the octopus male uses one of its eight arms, called Hectocotylus, to transfer his spermatophores (sperm-containing capsules) into the female’s mantle cavity during copulation. Octopuses have a highly complex nervous system, only part of which is localized in its brain, and an outstanding learning capability. They often break out of their aquariums in search of food. Some octopuses, such as the Mimic octopus (next page), move their arms in ways, that emulate the shape and movements of other sea creatures. A unique open sea octopus is Paper nautilus, of which the female secretes a special thin external shell by the greatly extended web of one pair of modified arms to contain itself and her hatched brood.

male

Cuttlefish (Sepia aculeata) female has its egg mass attached to the underside of stones. Squid (Sepiotheuthis sepioidea) sometimes swim in large schools. Photo: J. Dafni

84

female

A pair of White Spotted Octopus (Octopus macropus) copulating, and (below) in food search. Note the different and variable coloration. Female of a Paper Nautilus (Argonauta argo), cradled in its egg case. Photo: A. Gur, J. Dafni, N. Shashar

85

Octopus : Behavior

Mimic octopus

Octopuses show a wide range of behavioral patterns: aggressive postures, changing their shape to mimic patterns, as well as modes of movement – such as “jetting“ or even imitating other animals’ “walking” or “running”. Many of these behavioral patterns are unexplained. They use their environment to hide or ambush their prey. The octopus female displayed here usually enters empty bivalve shells to lay her eggs, but has been observed doing so in plastic cups.

The exceptional mimic octopus uses its arms, in their many arrangements, to mimic the shapes of sea stars, sea snakes and even fish (lionfish and flounders). It was discovered in Indonesia, and has been found lately in Eilat.

Unidentified octopus in an aggressive or ‘intimidating’ posture. Shell inhabiting octopus (Octopus marginatus) sheltering in a bivalve shell, apparently to hatch its eggs. Photo: D. Weinberg, I. Ben-Tov

Mimic Octopus (Thaumoctopus mimicus) in its natural habitat, among sea grasses: towering over its burrow, peeping out from inside, imitating a sea-snake and a brittle-star. Photo: J. Dafni

86

87

Crustaceans: Lobsters and prawns

Crustaceans: Crab variety

Macrura and Anomura: Clam-killer Slipper Lobster (Scyllarides tridacnophagus), Hermit Crab (Dardanus lagopodes) in an empty cone shell (Conus tessulatus); Marble Shrimp (Saron sp.) with long pincers. Photo: M. Levin, I. Ben-Tov, R. Biran

Decapoda Brachyura, Above: Variable Coral Crab (Carpilius convexus), largest brachyuran in Eilat’s reef, a male (the female color is uniform brown). Below right: coral Gall Crab (Hapalocarcinus marsupialis) gall and a female with big abdomen (inset), Carrier Crab (Dromia sp.), carrying a large sea squirt. Photo: B. Levi, J. Dafni, J. Poupin, D. Weinberg

Lobsters, prawn and shrimps are grouped in the order Decapoda Macrura, “Ten-legged, long abdomen”, shown on this page, whereas the “short abdomen” Brachyura are shown on the opposite page. They are too many to count here and only a representative few will be discussed. The Clam-killer slipper lobster is a nocturnal predator of giant clams, and the Marble shrimp has excessively long chelipeds. Hermit crabs are an intermediate group, Anomura, of crustaceans which hide their long soft abdomen in a dead snail’s shell, carrying it along.

88

The Brachyura, the short-abdomen crabs are the most advanced order of the Decapoda. Their short abdomen folds against the head-chest (cephalothorax), being widest in females, to store their eggs in the space between them. The coral crabs (page 31) reside between the coral branches, taking part in their defense. The Variable Coral crab strolls around the reef, feeding on anything that crosses its path. The Sponge Carrier crab uses corals, sponges or ascidians to hide and protect it from predators. In the coral gall crabs the female imprisons herself in a gall created by the branched coral. The dwarf male enters into this ‘cage’ to fertilize her, and she remains there to care for her offspring.

89

Echinoderms

Echinoderm Predator

The animals’ name, echinoderms, implies strangeness - “spiny-skinned”. Taxonomists grouped together several thousand animal species that sometimes differ from each other very much into the eccentric phylum Echinodermata. A deeper examination of their morphology and anatomy proves this to be the right decision. They share among them exclusive characteristics, shown by no other group. Their most distinctive trait is being exclusively marine – no echinoderm species ever ventured into inland waters or onto land. Moreover they are always considered – in history, art and lore – as symbols of the sea. The biology and physiology of echinoderms are also quite unique. Although they are invertebrates - lacking skeletal backbone - they show advanced anatomical peculiarities that group them in the Deuterostomia division, together with the better-known vertebrates. They show however many “primitive” phenomena: their symmetry is round, five-fold (pentaradial) and they have no legs or other locomotor appendages– yet they move around using tubefeet, long tiny pipes carrying an adhering disc, which are activated by a hydraulic mechanism termed water-vascular system, unique to echinoderms. They have no eyes, yet they show remarkable ability to tell light from dark, through light-sensitive pigments in their skin, and light plays an important role in the diel activity cycle of many echinoderms (e.g. feather-stars, sea-urchins, etc.). Their breeding is also different from any other animal group: they release eggs and sperm from a series of genital pores to produce swimming larvae. This reproductive behavior is ‘contagious’: once one animal has started, all sexually ripe individuals in the vicinity contribute their eggs and sperm. The fertilized egg develops into a floating larva (named pluteus in sea-urchins and brittle-stars, or auricularia in sea stars and sea cucumbers) that spends some weeks or even months drifting in the open sea before descending to the sea floor to settle down and develop into a crawling adult. The five classes differ in many aspects. While sea urchins are mainly grazers, sea stars are predators, able to prey on animals of their size or even – if the prey is strongly attached to the bottom – envelope their prey with the frontal part of their stomach, smothering it and starting to digest it externally. Feather stars and basket stars filter small planktonic organisms from the current, and sea-cucumbers eat ... sand! They move on the sea floor, ingest large amounts of sand, dig out the organic particles and excrete ‘sausages’ of cleaned sand. There are many more peculiarities in the morphology, anatomy and physiology of the echinoderms which justify the saying “strange is their middle name”. So strange that a famous American zoologist, Libby Henrietta Hyman, once wrote, that it seems that echinoderms were specially created in order to baffle the zoologist.

Many fish crave the internal organs of spiny echinoderms. The best-known are the Blue triggerfish, shown here. It blows water and exposes the sea urchin, turning it over to reach the less protected part of its body. Large wrasses are known to prey on brittle stars; they even seize long-spines sea urchins by their spines, carry and smash them onto rocks.

Five classes of echinoderms: Sea-cucumbers, Sea-urchins, Brittle-stars, Sea stars and Feather-stars. Photo: J. Dafni, M. Levin, A. Diamant

The ultimate echinoderm predator Blue Triggerfish (Pseudobalistes fuscus), crushing a Sand Dollar (Clypeaster humilis). Inset: half-buried (arrow) and exposed sand dollar. Photo: M. Levin; J. Dafni

90

91

Sea Stars

Do not be misled by the innocent beauty of the sea stars of the class Asteroidea, or as many erroneously call them, starfish. The serenity of this geometrically perfect creature hides a vicious predator of mollusks and other living creatures. They typically have five or more arms which radiate from an indistinct central disk. The mouth is in the lower center of the disk, but there is no anus. Sea stars do not rely on a jointed, movable skeleton for support and movement, but instead possess a hydraulic system for locomotion, based upon tubefeet on the lower part of the sea star’s arms. The Sea stars usually hunt for shelled animals such as oysters and clams. They have two stomachs, a frontal cardiac and a posterior pyloric one. The last one is used for digestion, while the cardiac stomach can be extended out of their mouth or even everted to engulf the prey. This feature allows the sea star to hunt prey that is much larger than its mouth would allow. Sea stars are known for the ability to regrow lost or damaged arms. In some sea stars, an entire sea star may be regenerated from a single arm attached to a portion of the central disk.

Sea Stars

The most influential tropical sea star – with a long term effect on entire reefs – is the Crownof-thorns sea star (COTS in short); referring to the crown of thorns that Jesus wore before his crucifixion. Having multiple (12-20) arms and a large size (up to 40cm), this sea star is well equipped with long venomous spines for protection. The COTS is a coral predator that preys upon coral colonies by climbing onto them, extruding its cardiac stomach over them, releasing digestive enzymes, and ingesting the decaying tissue. The COTS’s main enemy is the huge Triton trumpet snail (Charonia tritonis). The small Harlequin shrimps bite small pieces from the sea star, and may even kill it. Coral crabs (Trapezia spp.) are known to chase the COTS away from their host coral.

COTS populations strongly fluctuate, and since the 1970s large outbreaks of this species have caused the near demise of many Indo-Pacific coral reefs. These outbreaks are believed that to be caused by over-collection of the sea star predator, the tritons, while others blame pollutioninduced algal blooms that increased the survival of the COTS larvae. The Red Sea suffered several outbreaks. In the last one, in 1998, many thousands of Acanthaster sea stars were removed from Ras Mohammed Natural Park, Sinai. At Eilat they are relatively rare, but their population is monitored to avoid damage. From the largest to the smallest: Pigmy sea star is ca. 1-2 cm large, and has usually more than 5 arms. As the picture overleaf shows, it is the result of deliberate fission of the sea stars and regeneration of new arms, a form of asexual reproduction. They live unnoticed on the reef wall, scavenging coral and small sea anemone polyps.

Crown-of-thorns Sea star (Acanthaster planci): juvenile and an adult, devouring a branched coral. Right: Sea star predator, Harlequin Shrimp (Hymenocera elegans). Photo: J. Dafni, O. Lederman, A. Diamant

92

Common local sea stars: Cushion Sea star (Choriaster granulatus); Pearl Sea star (Fromia monilis); Pigmy Sea star (Asterina burtoni) fissiparous half (arrows point at the newly regenerating arms), and Ghardaqa Sea star (F. ghardaqana). Photo: L. Dafni, M. Levin, J. Dafni, B. Tamir

93

Sea Urchins

Sea urchins (class Echinoidea) have a circular body, either globular (as in the subclass Regularia) ovate or extremely flattened (as in the Irregularia). Their body is totally covered by an internal rigid shell (called test), made of close-fitting calcareous plates, with two openings: for the mouth in the lower (adoral) side, and the anus in the upper (adapical) side. In the regular sea urchins, five radii made of smaller plates, called ambulacra, stretch along the longitudinal axis, marked by tiny holes in the test, through which the ambulacral tubefeet emerge. These tubefeet adhere to the hard substrate and are either used to anchor the urchin in position, move it and even turn around. The test carries many large primary spines and more slender secondary spines, which in many species encircle the primaries. Special minute spines, equipped with three armed jaws called pedicellaria, may be mildly venomous. The sea urchin feeds with a specialized chewing device called “Aristotle’s lantern” made of five hard teeth, to scrape algae from the rock and erode the mineral rock into sand. Five sex pores encircle the anus, the gonopores, whence the sperm and eggs are released. A popular old joke asks: “How do sea urchins mate?” The answer is “Very, very carefully, because of the spines”. In fact, the spines are the main obstacle which prevents us from totally engrossing ourselves in the beauty of the reef. The long and sharp spine ‘forest’ of the Long-spine urchin is a haven for many creatures - fish, shrimps, prawns, small cuttlefish, nocturnal fish who seek shelter during daylight and many more. Paradoxically, another black urchin species, Double-spined urchin, with blunt primary spines, is the most fearful urchin. The secondary spines hidden between its primary spines are needle-sharp and their sting causes acute pain. They are apparently the most efficient of the reef protectors: they keep away many evildoers. Anyway, if your intentions are good, just avoid touching them! In contrast to the above mentioned species, most sea urchins in Eilat reefs are harmless. Even the poisonous Fire urchin is so rare that its menace can be easily overlooked. A toxic sea urchin of the tropical family Toxopneustidae is the Short-spined velvet sea urchin. It is the largest and one of the most variable species. This species has been subject to bizarre deformations due to sea pollution (page 158).

Sea urchins: Regular or Irregular

The regular sea urchins are globular, and radially symmetrical. Sea urchins of the other group, the Irregularia, are bilaterally symmetrical and have a distinct length axis and orientation. They are divided into (1) the flattened Sand dollars (order Clypeasteroida), whose mouth is in the ventral (lower) middle of the skeleton, but the anus is far behind in the ventral side, and (2) the almost globular Heart urchins (order Spatangoida) whose mouth is in the frontal ventral side (M, in the picture below) and the anus is in the posterior edge. Since all the irregular sea urchins burrow in the sand, the tubefeet system is much reduced and used mainly as respiratory organ, in a flower-shape petaloid. They use their spines as oars or paddles to move beneath the sand surface. The urchins of the former group are flat and move slowly at shallow depth; it is easy to locate them through their wide sand marks, whereas the heart urchins dig deeper and move faster, leaving no trace on the sand.

M

Irregular echinoids: Common Sand Dollar (Clypeaster humilis) half-buried in sand and another one, fully exposed; a Fissured Sand Dollar (Echinodiscus auritus). Bottom left: Spiny Heart Urchin (Lovenia elongata) ventral face and a Helmet Shell (Casmaria sp.) killing this urchin. Photo: J. Dafni, M. Levin

A gallery of regular Sea urchins: Ten-lined Urchin (Eucidaris metularia), Velvet Sea Urchin (Tripneustes gratilla elatensis); Double-Spined urchin (Echinothrix calamaris); Fire Urchin (Asthenosoma marisrubri), Geometric Urchin (Microcyphus rousseaui) and Slate Pencil Urchin (Heterocentrotus mammilatus). Photo: J. Dafni, M. Levin, I. Ben-Tov

94

95

Sea Cucumbers

Sea cucumbers are echinoderms of the class Holothuroidea that have an elongated worm-like body covered with thick skin. They crawl on the sea floor ingesting sand, digest the organic matter and excrete their droppings as sausage-like sand strings. Their skeleton is reduced to typical imbedded calcite ossicles, whose shapes are species-specific, by which the precise identification of sea cucumber species is made. Most common sea cucumbers of the order Aspidochirota (=shield-hand), are favored food in the Far East, under the name “trepang”. A fish parasite, pearlfish (Carapus sp.) enters the cucumber through its anus, and feasts on its intestine. A probable means of protection against this pest are the five anal teeth that surround the anus of the sea cucumber Actinopyga (see opposite page).

More on Sea Cucumbers

Behavior: When disturbed, the half-buried Sticky Sea Cucumber (Holothuria impatiens) ejects sticky threads called Cuvierian tubules, to deter and obstruct enemies. Left: Upright posture of the sea cucumber Actinopyga bannwarthi, shared by all ripe members in the area at reproduction, when they synchronically eject eggs and semen. A semen string is shown in the far right corner of the picture. Fertilization takes place in the water. Photo: J. Dafni, K. Levy The second order of cucumbers is Rope cucumbers, Apodida. These flexible, elongated snake-like creatures lack tubefeet, moving about by peristaltic contraction of their peripheral muscles, using their skin’s anchor-like ossicles to hold to the ground, gathering food with their long oral tentacles.

Sea Cucumbers: Black Sea Cucumber (Holothuria atra), sea floor feeding and with excreted sand string; Tubercle Sea Cucumber (Stichopus sp.); Noble Sea Cucumber (Holothuria nobilis); Tigertail Sea Cucumber (H. hilla) and Edible Sea Cucumber (H. edulis). Photo: J. Dafni, M. Levin

96

Black Rope-Cucumber (Synapta reciprocans), Grey Rope Cucumber (Opheodesoma grisea), and Greenish Synapta, (Euapta godeffroyi). Photo: B. Tamir, M. Levin, J. Dafni

97

Brittle Stars

Feather- and Basket Stars

Subtidal Brittle Star (Macrophiothrix hirsuta), Speckled Brittle Star (Ophiocoma valenciae) and Reef Brittle Star (Ophiothrix propinqua) associated with a large Tube Sponge (Callispongia sp.). Another bizarre ophiuroid is the Basket Star, shown in the opposite page. Photo: J. Dafni, M. Levin

Reef Feather Star (Lamprometra klunzingeri) with extended, or with folded arms. Below left: Juvenile Basket Star (Astroboa nuda) reposing among soft coral branches. Photo: I. Ben-Tov, M. Levin

Brittle stars, class Ophiuroidea, are closely related to sea stars. They generally have five long, slender, whip-like arms. Unlike sea stars, they use the flexible arms, consisted of vertebra-like calcareous disks, to crawl or cling to solid objects, such as sponges or corals. The tubefeet are used mainly to collect food and move it to the mouth, situated in the lower middle of the disk, and there is no anus. Reef inhabiting stars are small, and readily overlooked. They resist predation by self-amputation of arms, and their later regeneration.

98

Feather stars represent the echinoderm class Crinoidea. They are nocturnal animals that spread their arms against the current to trap small planktonic organisms and carry them to the mouth in its center. During the day they hide in shaded crevices with folded arms. At late afternoon they emerge, crawl upwards and hold fast to the reef top by the short flexible finger-like cirri, spreading their arms against the plankton-rich current. The Basket star is similar in its behavior, but belongs to the brittle stars (class Ophiuroidea – see opposite page). Although both have no eyes they are able to sense the light, and their diel activity is triggered by light or darkness.

99

Sea Squirts

Sea squirts or Ascidia are the most primitive group in the phylum Chordata, and at the same time they are included among the invertebrates. They possess a central nerve chord (notochord) at their larval ‘tadpole stage’, losing it later in life when they are developed into sac-like solitary sessile animals or complex colonies of the same, often mistaken for sponges. They extract their food from seawater, taken in through an oral siphon, flowing through mucus-covered gill slits into a chamber called the atrium, and exiting through the atrial siphon. They are covered by a tough outer “tunic”, hence their alternative name Tunicata.

Tunicata: Salps

Salps are planktonic barrel-shaped tunicates, swimming by contraction, pumping water through their transparent gelatinous bodies. They strain the pumped water and feed on phytoplankton. Salps reproduce asexually, forming long living colony chains seen in the water column at Eilat.

Giant Salp string (Salpa maxima), an infrequent visitor. Inset: a solitary salp invaded by a Pram Bug Amphipod (Phronima sp.). Photo: M. Shpigel. Y. Esh.

Hemichordata: Acorn Worms

Hemichordata is a sub-phylum related to the chordata. The only representative of this group in our area is the Acorn worm. It lives buried deep in the sand, using its smooth proboscis and gill slits to sieve organic particles from the wet sediments in which it is embedded. The acorn worm is very seldom seen on the surface. More commonly found are its excreted sand strings emerging from below, like toothpaste from its tube.

Above: A Solitary Sea Squirt showing its oral and atrial siphons. Below: Two color variations of compound or Social Ascidian (Botryllus eilatensis) showing many small oral openings and larger atrial siphons. Photo: J. Dafni

100

Acorn Worm (Ptychodera flava) sand paste emerging from the bottom. Photo: J. Dafni

101

Reef Fish

Reef Fish

The high reef fish diversity is well illustrated in the above picture. Six fishes each of a different species are gathered in one frame: Broomtail Wrasse, Klunzinger’s Wrasse, Parrotfish, Snake Eel and a Speckled Sand Perch showing interest in a Blue Triggerfish (Pseudobalistes fuscus) burrowing in the sand for sea urchins. Photo: M. Levin

It is hard to imagine a coral reef without the colorful and lively coral fishes. Without them this seascape would have been dull and uninviting. Two main fish families are shown in these pictures, the Groupers (Serranidae) and the Damselfishes (Pomacentridae). We will address them in more detail in the coming pages. Photo: M. Levin

Of all the creatures dwelling on coral reefs, none are more colorful and vivacious than the fishes. The high diversity of the fish communities in the coral reefs is maintained mainly by the reef’s complexity, which translates into many different types of foods, shelter, and motion and reproduction opportunities. Of the more than 1200 species living in the Red Sea, approximately half have been recorded at Eilat, most of them in the reef environment. Below we will show the most common, interesting or exceptional species. Contrary to the invertebrate planktonic drifters, fish are termed nekton, meaning “swimmers.

102

103

Sharks

Sharks are fish of the subclass Elasmobranchii, with a cartilaginous skeleton and a typically streamlined body. They extract oxygen from seawater as it passes over their gills, exiting through five gill slits. The shark’s body is covered by small dermal denticles that are also used as replaceable larger teeth. Unfortunately, reef sharks are entirely missing from Eilat - they obviously lost in the competition with man. Yet several sharks are met occasionally: in deeper water the small Hound Shark (Iago omanensis) is rather common. In shallow water Whale Sharks – the largest fish on earth - visit the shore once or twice a year. This shark feeds on small plankton oraganism like the crustacean Krill, the favorite food of baleen whales, which are abundant in temperate seas, and infrequently become stranded on the beach.

Recent shark encounters (Above): Two photographs of a welcomed Whale Shark (Rhincodon typus), photographed while swimming along the shore in the summer of 2005. Below right to left: an unidentified Mako Shark (Isurus sp.), an infrequent visitor, attracted to the fish cages near Eilat northern shore and Krill (Euphasia sp.) Photo: J. Grinfeld, A. Kendler, M. Levin, J. Dafni

104

Batoidea- Skates and Rays

Skates and rays are also of the Elasmobranchia. Their pectoral fins merge with their heads, forming frontally large disc-like bodies. The frontal part is flat to facilitate resting and preying on the sea bottom, while the posterior part is reduced, in some cases ending with a long thread-like tail. Unlike the sharks (order Selachii) having lateral gill slits, fish of the order Batoidea always have their gill slits in the ventral (lower) surface of the flat body.

The common reef Sting Ray (Taeniura lymma) usually rests in the lagoon, occasionally half-buried in the sand. The Electric Ray (Torpedo sinuspersici) uses its electric organs to stun and hunt its prey, and as a weapon. Photo: J. Dafni, M. Levin

105

Batoidea- Skates and rays

Among the largest rays there is an evolutionary tendency to return to swim in midwater, shown by Eagle rays. Their pectoral fins are pointed sideways, and the eagle rays use them in a way similar to birds’ wings. A step forward was made by Manta rays who adopted midwater swimming and plankton feeding similar to the whale shark.

Eagle Ray (Aetobatus narinari), a good swimmer hunts animals buried in the sand, such as hiding fish, also using an electro-sensory mechanism; and Manta Rays (Manta birostris), a midwater plankton feeder. Below: Oral lobes of the Manta Ray. The picture shows also several Suckerfish (Echeneis naucrates) hitching a ride close to the manta ray’s ventral surface. Photo: B. Tamir, I. Ben-Tov

106

Fish as Predators

Most of the fishes are predators, and only a small percentage eats plants. A vegetarian diet requires anatomical adaptations such as longer intestines, specialized teeth, and in many cases symbiotic bacteria in the gut. None of the sharks, the most primitive fish, are herbivorous. For most fish, predation is the rule. Large-prey predators hunt either singly, ambushing their prey, or in schools. Some, like lionfish and groupers, swim among their prey, waiting for an opportunity to pick off sick or weak fish.

Two predators, two tactics: Above, Common Lizardfish (Synodus variegatus) ambushes passing fish. Below: Pigmy Sweepers (Parapriacanthus guentheri) keep a safe distance from a Redmouth Grouper (Aethaloperca rogaa) that swims among them. Photo: I. Ben-Tov, J. Dafni

107

Eels and Moray eels

The eels (order Anguilliformes) have many representatives in tropical waters. The most common are Moray eels (family Muraenidae). They are large, multi-colored and resourceful nocturnal predators, hiding daily in crevices or meandering between the corals. Other eels are the subterranean Snake eels, and last but not least, the Garden eels, plankton feeders that live in permanent holes in large colonies, forming a spectacular attraction in Eilat’s seaward shallow sea floor.

Common reef moray eels: Snowflake Moray (Echidna nebulosa), Grey Moray (Siderea grisea), Yellowmargin Moray (Gymnothorax flavimarginatus) and Zebra Moray (Gymnomuraena zebra). (Another moray species is shown on page 115). Photo: Y. Aharoni, J. Dafni, M. Levin, E. Halevy

108

Sand Dwelling Eels

Adapted to subterranean life, the Snake eels (Ophichtidae) have a narrow body and pointed head. The common Marbled snake eel is known to divers by its head popping out of the sand. When moving it leaves a zigzag pattern in the sand. No less unique are the Garden eels of the familiy Congridae, hundreds of which live in three large colonies, each burrowed in permanent holes in the sand, at a depth of 7-15 m off the southern beach of Eilat. They stay in their individual burrows, catching passing plankton. Potential mates stretch over from adjacent burrows and entwine their bodies.

Spotted Snake Eel (Myrichthys maculosus), mimicking the pattern of venomous sea snakes (common in the Indian Ocean but luckily entirely missing from the Red Sea); Marbled Snake Eel (Callechelys marmorata) in a typical head-out posture and an exposed animal, possibly in stress. Below: Garden Eels (Gorgasia sillneri) in their colony, forming a unique habitat, known as “Eel Garden”. Photo: Z. Movshowits, M. Levin, J. Dafni

109

Sea horses and Shrimpfishes

Pipefish and Ghost pipefish

Shrimpfish (Aeoliscus punctulatus), moving and hiding among sea urchins spines; Common Pipefish (Corythoichthys shultzi) group on a Favia coral, and a solitary Thorny Seahorse (Hippocampus histrix). Photo: J. Dafni, M. Levin, Y. Aharoni

Pipefish: Multibar Pipefish (Dunkerocampus multiannulatus), middle row, pair of Coral Ghostfishes (Solenostomus paradoxus), the larger female shows its brooding pouch, and below, two color varieties of the Seagrass Ghostfish (Solenostomus cyanopterus). Photo: Y. Aharoni, M. Levin, B. Tamir

In the order Syngnathiformes are included some of the most bizarre fish-species – Seahorses, Pipefishes, Ghost- and Cornetfishes. Their scientific name refers to the typical long, tube-like snout, made of fused jaws. Another peculiarity: in fish of the family Syngnathidae males have a brood pouch in which the female deposits the eggs; the males fertilize and incubate them.

110

Pipefishes are relatives of the seahorse. They share their male brooding habit. Ghost pipefishes are different; they are perfectly camouflaged and blend in among algae or seagrass for protection. The exquisitely colored Coral Ghostfish fits the color of soft corals. Contrary to most pipefish, the ghost pipefish female carries her eggs in a modified brooding pouch, made of its enlarged pelvic fins. All are plankton feeders.

111

Dragon fish

Lionfish and prey

Dragonfish (Eurypegasus draconis) pair and a frontal look at the fish. Photo: M. Levin, J. Dafni

Lionfish (Pterois miles) keeping watch over Basslets (Pseudanthias squamipinnis). Below: An unexplained ‘flag’ - a rare colored head tentacle – frequently seen in local lionfish. Photo: M. Levin, B. Tamir

Surprisingly, this strange creature is rather common in Eilat’s lagoons. Their scientific name, Pegasus reminds us of the mythological winged horse that the Greek hero Perseus rode to rescue Andromeda, chained to the rocks of Jaffa, from a terrible sea monster. The dragon-shaped fish, completely encased in tough bony plates, is otherwise vulnerable, and it seems as if they were named so as a joke. The alternative name, Seamoth, may better describe them. These fish translucent ‘winged’ pectoral fins are unfit for swimming or gliding, rather for crawling slowly on the coarse sand in pairs, using their pelvic fin rays as digits. They have no swim bladder and barely swim. The thick skin protects them from predation, while they feed on small organic debris, with their tiny mouth, hidden beneath an elongated snout.

112

Unlike other members of the venomous scorpion fish family Scorpaenidae, Lionfish are not camouflaged (claims have been raised that in their normal hunting behavior they imitate feather stars or other innocent creatures or non-living objects), and slowly patrol the reef edge, stalking their fish prey. They are active in the early mornings and late afternoons, sometimes in hunting groups not unlike a lion pack.

113

Scorpion fish and Stone fish

In the next two pages, other members of the scorpionfish family, subfamilies of scorpionfishes and stonefishes are discussed. They are armed with highly venomous dorsal spines to discourage bigger fish who might attack them while they lie in wait for prey. Particularly venomous are stonefish, which are so perfectly camouflaged that even the breathing ‘pumping’ movement of the gill covers and mouth is obscured. The Devil scorpionfish, when threatened, upturns its lower side of its pectoral fins, exposing for a ‘blink of an eye’ the bright colors of the lower surface, as a startling warning to its potential enemy.

Shortfin Lionfish (Dendrochirus brachypterus) and Clearfin Lionfish (Pterois radiata) challenge their enemies with their flamboyant red color; Devil Scorpionfish (Scorpaenopsis diabolus), camouflaged, and showing its warning colors (inset). Photo: J. Dafni

114

Stonefish

The Stonefish is a carnivorous fish armed with 13 venomous dorsal spines. It usually rests on the ground, perfectly blending with its surrounding, to ambush its prey. When threatened it spreads its fins, exposing its spines. Its relation, the stingfish lives on lagunar sand, moving along using its pectoral rays as “fingers”. To advertise its venom, the stingfish flares the underside of its pectoral fins, and spreads its tail flash showing a defiant exquisite warning coloration.

Two members of the stonefish subfamily (Synanceinae) of the scorpionfish: the perfectly camouflaged Stonefish (Synanceia verrucosa), and the Two-Stick Stingfish (Inimicus filamentosus) in warning display. Photo: K. Levy, J. Dafni

115

Groupers

Basslets or Goldies

Groupers have a large head and heavy body, and spiny dorsal fins. Some grouper species rank among the largest top predators (except sharks) of the reef environment. They relate to the Serranidae, the largest family in the order Perciformes. At least 20 species of groupers are present in the Red Sea, most of them encountered in Eilat’s reefs. The most common and the smallest among them is the Blacktip grouper, and the largest – which lives long enough to reach the size of 80 cm – is the Lunartail grouper. Somewhat smaller are the Coral groupers. They were hunted by spear fishermen in the past, and since their size is age-dependent, their average size decreased. Protection measures taken at present have started to affect their numbers and increase their size.

There is no question which is the most photogenic fish in the reefs of Eilat. It is the Fairy basslet, known also as Goldy, a pink or orange fish; no reef photograph will be perfect without its orange tinge. Basslets comprise the subfamily Anthiinae of the grouper family Serranidae. These agile plankton feeders swarm around every coral knoll or reef front, always facing the incoming current. Basslets are protogynous hermaphrodites, meaning that they are born females, to live in “harems” of up to a dozen females for the most productive part of their life, always surrounded by fewer dominant males. The territorial males perform an acrobatic U-swim (dive and rise) display and vigorously defend the water section they consider their ‘plot’. Non-territorial males join a “bachelors’” school, ready to take over if a dominant male perishes. Alternatively, an alpha female will change its sex to become a dominant male. At depths greater than 20m another species, the striped basslets, is common.

Four typical Eilati groupers: Blacktip Grouper (Epinephelus fasciatus), Lunartail Grouper (Variola louti), Coral Grouper (Cephalopholis miniatus) and Red Sea Roving Grouper (Plectropomus pessuliferus marisrubri). An additional grouper – Redmouth Grouper (Aethaloperca rogaa) - is shown on page 107. Photo: J. Dafni, M. Levin

Above: A school of orange colored Fairy Basslets (Pseudanthias squamipinnis): females and several violet-pink males shown in the lower half. Below, male (right) and a female. Striped Basslets (P. taeniatus), males in deeper water. Photo: J. Dafni, M. Levin, R. Koslawsky

116

117

Butterflyfishes

The animals went in, two by two…

Six common Butterflyfishes from Eilat: Crown Butterflyfish (Chaetodon paucifasciata), Threadfin Butterflyfish (C. auriga), Masked Butterflyfish (C. semilarvatus), Striped Butterflyfish (C. fasciatus), Lined Butterflyfish (C. lineolatus) and Chevron Butterflyfish (C. trifascialis). Photo: J. Dafni, M. Levin

Butterflyfish pairs: Crown Butterflyfish (Chaetodon paucifasciata), Threadfin Butterflyfish (C. auriga), Exquisite Butterflyfish (C. austriacus), a school of Bannerfishes (Heniochus diphreutes) and Lined Butterflyfish (C. lineolatus). Photo: J. Dafni, M. Levin

Butterflyfishes are conspicuous tropical reef fish of the family Chaetodontidae. About 15 species live in the northern Gulf of Aqaba. They are named for their brightly colored and striking patterns in shades of black, yellow, red and orange. Their deep, laterally compressed bodies are eye-catching in the reef background. Since they have no weapon for self-defense, they rely on deception to ward off enemies. Most species have dark bands or patch across their eyes, and some have bogus eyespots on their flanks, to deceive or intimidate predators. Butterflyfishes feed on coral polyps. They are territorial, swimming in pairs along the reef flats. By night they hide amongst the crevices of the reef and some exhibit markedly different night coloration pattern. Below and overleaf are 8 common local species:

118

Butterflyfishes have brought pair bonding almost to perfection. They most frequently move together, male and female. Even within a school, pairs are very often visible.

119

Angelfishes

Marine angelfishes, of the family Pomacanthidae, are related to the butterfly fishes. In Hebrew they are called Emperors, and indeed, they are large, colorful and majestic. They differ from butterflyfish by having a color-enhanced sharp spine for protection emerging behind the gill covers (hence their scientific name “mouth-spined”). Their poster-colored compressed bodies possibly provide a territorial declaration. Their aggressive behavior is apparently the reason why the colors of angelfish juveniles often differ markedly from the adults, possibly aimed to avoid being attacked by them. Angelfishes are never abundant; only the smallest species go in pairs. Yellowbar angelfish is the largest. Emperor angelfishes and Royal angelfishes, although smaller, exhibit more vibrant coloration.

Yellowbar Angelfish (Pomacanthus maculosus), adult and juvenile (inset). Photo: M. Levin

120

more Angelfishes

Royal Angelfish (Pygoplites diacanthus); Yellow-ear Angelfish (Holacanthus xanthotis) and below, Emperor Angelfish (Pomacanthus imperator) adult and juvenile (inset). Photo: M. Levin, J. Dafni, A. Diamant

121

Damsel fish

Damselfishes in action

Damselfishes, members of the family Pomacentridae, are among the most common smaller fish species associated with coral reefs. They form territorial schools or associations - dominated by a male or in some cases by a dominant female. During the day they venture out to open water, feeding on zooplankton, hurrying back in case of emergency or during the night to hide among the coral branches. In the mating season, males adopt conspicuous ‘poster coloration’, choosing a smaller or larger rock plot whereto the females are invited to lay their eggs, upon which the males eject their semen. The males then protect the eggs until they hatch and the tiny fingerlings are carried away by the currents to find a new home. Damselfishes are protogynous sequential hermaphrodites (female first) sex change. Others like the clownfish show protandrous (malefirst) sex change.

Damselfishes are territorial fish, always attached to an anemone or a branching coral. They seek shelter there when alarmed. It has been found that by wriggling their fins and tails at night the damselfishes aerate the space between the coral branches, improving the coral metabolism. Most damselfish use the coral environment as preferred breeding sites.

Typical damselfishes: Sergeant Majors (Abudefduf saxatilis and A. sexfasciatus, behind), Banded Dascyllus (Dascyllus aruanus), Domino Dascyllus (D. trimaculatus) pair (mating male is grey), Green Chromis (Chromis viridis) (male), Sulphur Damselfish (Pomacentrus sulfureus), Royal Damselfish (Paraglyphidodon melas), a colored juvenile (adult is pitch black) and Footballer Damselfish (Chrysoptera annulata). Photo: J. Dafni, M. Levin

Damselfish interactions: Clownfish (Amphiprion bicinctus) symbiotic with a Cushion Anemone (Stoichactis gigas), Green Chromis (Chromis viridis) and blue juveniles (inset), surrounding their home base, a Staghorn coral. The Banded Dascyllus (Dascyllus aruanus) shelters in a Stylophora colony, frequently together with other damselfish. Photo: M. Levin, J. Dafni

122

123

Wrasses

Coral fish of the family Labridae (=lip fish), are among the most abundant and conspicuous fishes in tropical reefs around the world. There are approximately 50 species in the Gulf of Aqaba. They appear in a diverse range of colors, shapes and sizes, often varying considerably according to their age and the available food. Wrasses feed on a large variety of invertebrates, and zooplankton. Some wrasses have protractile mouths, pointed snout to collect worms, or thick lips and canine teeth to crush mollusk shells and sea urchin skeletons. Some wrasses fill a useful role in the coral fish community as cleaners. Few wrasses are sexually dimorphic, organized into harem-based social systems and exhibit protogynous sex change. Juveniles are often different from their parents.

Common wrasses: Klunzinger’s Wrasse (Thalassoma klunzingeri), Thicklip Wrasse (Hemigymnus fasciatus), Bird Wrasse (Gomphosus coeruleus), male (female see in page 181), Yellowtail Wrasse (Anampses meleagrides), Spottail Wrasse (Coris caudimacula), Clown Wrasse (Coris aygula) adult and juvenile, Eightline Wrasse (Parachelilinus octotaenia) and Hog Wrasse (Bodianus anthoides). Photo: J. Dafni, R. Koslawsky, Z. Movshowits, M. Levin

124

Wrasses in action

The Broomtail wrasse is the largest wrasse in Eilat’s coral reef. The mature males reach 50 cm and show a long and tattered tail. A small vertical orange half moon-shaped mark, displayed at all ages, is a helpful identification aid, reflected in its scientific name. This wrasse feeds on spiny sea urchins, among other prey, smashing their hard shells on the reef wall.

Broomtail Wrasse (Cheilinus lunulatus), attended by two Cleaner Wrasses (Labroides dimidiatus) (see next page). Right Inset: juvenile Broomtail Wrasse. Left inset: Broomtail Wrasse wounded by Long Spine urchin spines. Photo: J. Dafni, Y. Aharoni.

125

Cleaning stations

Who else is in the Cleaners’ guild?

Cleaner Wrasse (Labroides dimidiatus) with Damselfish (Dascyllus trimaculatus) and while cleaning a gaping Needlefish (Tylosurus sp.). Spottail wrasse (Coris caudimacula) was also seen several times approaching fish in a similar way. Photo: I. Ben-tov, D. Weinberg, J. Dafni

Variety of cleaners: Banded Boxer shrimp (Stenopus hispidus), and White Banded Cleaner Shrimp (Lysmata amboinensis), displaying their advertising white antennae, and while cleaning a Yellowmouthed Moray (Gymnothorax nudivomer) teeth. Partner Shrimps: Pereclimenes imperator keeps a sea cucumber’s skin clean and the transparent Pereclimenes longicarpus cleans a Lizardfish. The Squat Cleaner Shrimp (Thor amboinensis) is associated with sea anemone, removing organic debris from its surface. Photo: J. Dafni, M. Levin, A. Stern, I. Ben-tov, B. Tamir, E. Halevi

A cleaning station is a location in the reef vicinity where fish congregate to be cleaned by cleaner-fish or shrimps. The cleaners remove parasites and dead skin from their ‘clients’ bodies. The principal cleaner is the cleaner wrasse, which has developed a special behavioral pattern to advertise its services: it swims in a kind of wavy ‘dance’, pursuing and slightly touching approaching fish. The fishes to be cleaned show their interest by posing in unconventional ways, even changing their color pattern – possibly to highlight the parasite or dead tissue – and opening their mouths and gill covers to facilitate the cleaner’s approach. The cleaner wrasse removes the parasites directly from the cleaned fish skin. Cleaning stations are often located in cave entrances or on top of a coral head. The cleaner wrasse genus Labroides is the most specialized. All of its species are cleaners. But cleaning is also performed by other wrasses. Juveniles of the Fourline cleaner wrasse are similar in shape and behavior to those of the common cleaner, while the adult changes its feeding habits. An experiment done in the 1960’s showed that removal of the cleaner fishes from a coral reef resulted in a significant reduction in fish numbers and an increase of dermal infections in the remaining fishes.

126

Cleaner shrimps are long-tailed ‘swimming’ crustaceans (suborder Natantia) that also clean fish at their own cleaning sites. Cave-dwelling fish, like moray eels and smaller schooling fish too small for cleaner wrasses, are attended by these shrimps. Several families have one or several members who do this job. The most common cleaner shrimp is Banded boxer shrimp of the family Stenopodidae; another common cleaner is White banded cleaner shrimp of the Hyppolytidae. The smaller Squat cleaner shrimp cleans the sea anemone, to which it is commensal.

127

Parrot Fish

The Parrotfish (genus Scarus) is a notable example of specialization and diversity among reef fish. It is named after both, its beaklike dental plates made of fused teeth and its brilliant coloration patterns. A special adaptation for scraping algae includes the stone-cutting beak and pharyngeal teeth, a grinding device inside the pharynx made of two bony toothed grinding plates which turn the calcareous pieces into chalky paste from which algal material is digested in its gut, exiting pure calcareous sand through the anus.

Heavybeak Parrotfish (Scarus gibbus), male. Photo: J. Dafni

128

Variations on a theme

Parrotfish are the main coral reef eroder. The fifteen parrotfish species in the Gulf exhibit bewildering color diversity because of their sexual dimorphism – females differ from males, and juveniles have their own coloration patterns. Like many coral fish they exhibit protogynous sex change. The so-called ‘terminal males’ show the most intense and vibrant coloration. Parrotfish are mainly diurnal feeders. At night they seek shelter inside caves and crevices where they lay immobile, some even produce a transparent mucous ‘blanket’ to mask their scent from predators. The following shows pictures of four of the common parrotfish species - males, females and juvenile - on Eilat’s reefs. All are common at the “Caves” site, at a depth of 1-5m.

Common Eilat Parrotfishes, left males and right, females, top to bottom: Dusky Parrotfish (Scarus niger), Heavybeak Parrotfish. (S. gibbus) Bullethead Parrotfish (S. sordidus) and Bicolor Parrotfish (S. bicolor), male, female and a juvenile (inset). Photo: J. Dafni

129

Goatfish

Hawkfish

Red Sea Goatfish (Parupeneus forsskali) searching for food, while a Spinecheek (Scolopsis ghanam) watches from above. Below left: a small wrasse accompanies the goatfishes, hoping to get a bite. Note the variety of colors, displayed by one species. Another goatfish (P. cyclostomus) is shown in page 181. Photo: J. Dafni

Hawkfish. Above: two color forms of the Blotched Hawkfish (Parachirrhites forsteri) on ambush. Middle: Pixy Hawkfish (Cirrhitichthys oxycephalus) and Longnose Hawkfish (Oxychirrites typus), below. Photo: M. Levin, B. Tamir, J. Dafni

Goatfishes are tropical fish of the family Mullidae. They extract food from the sea floor, using a pair of long barbels protruding from their chins to dig out worms and mollusks of the sand. The barbels are also chemosensory organs, able to locate buried food. Several fish species accompany them, hoping to share in the booty.

130

Hawkfishes, family Cirrhitidae, are small predatory fishes. They have large heads with thick, somewhat elongated bodies. Their anterior dorsal spines have several trailing fringing filaments - termed cirri - on their tips, hence the scientific family name meaning “fringe fins“. The Pixy hawkfish is one of the most colorful fish in Eilat’s reefs. A distinguished relative is the Longnose hawkfish, associated with large sea fans. (See also page 67).

131

Flat fish

Flatfish are deformed fishes, which underwent an evolutionary modification to swim sideways: during ontogeny (individual development) one eye migrates from the “blind side” around the head, the dorsal and anal fins elongated, and the anus, usually in the rear end of the body moved toward the head, pushed forwards by the elongating anal fin. Thus, a new symmetry has developed - both eyes lie on one side of the head, and the entire body lies on one side. They are naturally camouflaged and often hide in the sand. The common species Leopard flounder has both eyes on the left side, whereas Moses sole has them on the right. The last species is known to emit a milky poisonous substance known to deter sharks.

Leopard Flounder (Bothus pantherinus) and Moses Sole (Pardachirus marmoratus). Note the opposite orientation – left in the former, right in the latter – and the lateral line seen along the middle of the former’s body. Photo: J. Dafni

132

Low-lying fish

Fish living on sand without shelter must adapt both in shape and coloration to the uniform environment. This may involve either becoming extremely flattened, or by behavior. Three types of flat fish are found in Eilat: the cartilaginous skates and rays (see page 105), and fish of the Flathead family, such as the Crocodile fish, obtain the low profile by flattening their dorsoventral axis. The other type are the side-lying flounders (opposite page). Stonefish, Stargazers and Lizardfish adapt by burrowing in the sand (page 153).

Above and middle left: a side and frontal view of the flat headed Crocodile Fish (Papilloculiceps longiceps), a large predator. Below: the Arabian Tongue Sole (Cynoglossus sinusarabici), a flatfish. Note that both the elongated dorsal and anal fins that reach the mouth, enabling the fish to swim on its side, and the lateral line at its midst. Their ‘blind’ side facing the seafloor is colorless, and lacks a lateral line. Middle right: the same fish’ twisted mouth. Photo: J. Dafni, M. Levin

133

Blennies

Blennies – family Blennidae – are small fish with elongated and flexible bodies. A pair of whiskerlike cirri often protrudes from their forehead. Most of them are benthic (bottom oriented), burrowing in the sand or dwelling inside empty shells of worms or tube-shaped mollusk shells. They are superficially similar to members of the Gobiidae. Due to the lack of swim bladders, they are not neutrally buoyant, and normally rest on the hard substratum, or in their hiding crevices. A specialized member of this family is the Sabretoothed blenny, which mimics the color pattern of a cleaner fish and bites off pieces of skin and scales from its “clients”.

More Blennies…

Red Sea Leaping Blenny (Alticus kirkii) is an amphibious fish, perches on rocks, sticking out of the sea, and feeds on benthic algae. In an emergency it leaps to other rocks so quickly that it barely dips in the water. It breathes both air and oxygen dissolved in water. Highfin Blenny (Petroscirtes mitratus) is a small fish found near seaweed covered piers and floating objects. The male has a typical elevated frontal fin. Other blennies appearing in the reef are Arabian Fangblenny (Petroscirtes ancylodon) and Sabretoothed Blenny (Plagiotremus rhinorhynchus), an aggressive fish which pesters and bites divers and shelters in tube snail’s shells. Photo: J. Dafni, M. Levin

.…and Nocturnal Predators

Cardinalfish family Apogonidae, and Soldierfish (Holocentridae) are the main small and medium-sized nocturnal predators (see also page 142). During the day they congregate, and inhabit all the reef’s nooks and crannies.

Above: Lance Blenny (Aspidontus dussumieri), a solitary fish that hides in empty tube snail shells (above right of picture), venturing out to feed on algae and organic debris. Shortbodied Blenny (Exallias brevis) lives among Fire Coral (Millepora) plates; an innocent Mimic Blenny (Ecsenius gravieri) imitates another, bite-inflicting Blackline Blenny (Meiacanthus nigrolineatus) (not shown); and Rockskipper (Istiblennius edentulus). Photo: J. Dafni, I. Ben-Tov

134

The small Goldstriped Cardinalfish (Apogon cyanosoma) is nocturnal. Male of a Tiger Cardinalfish (Cheilodipterus sp.), mouth brooding the eggs laid by the female. Photo: J. Dafni, D. Weinberg

135

Gobies

Gobies, family Gobiidae, are small bottom-adapted fishes, able to use their fused pelvic fins as disc-shaped suckers to adhere to the rocky substratum to resist waves. They form symbiotic relations with other organisms. The special relation between the goby and the Bulldozer shrimp was initially studied at Eilat. The shrimp, almost blind behind the sand it carries out of its burrow, depends on the goby to warn against danger, in which case they both rush into the burrow. The shrimp ‘keeps in touch’ with its “sentry” by constantly stroking it with its long antennae.

Above: two Shrimp gobies (Cryptocentrus steinitzi) are shown sharing a burrow with a Bulldozer shrimp (Alpheus djibutensis) for protection. Below: The Graceful goby (Lotilia graciliosa) hovers over its “partner” shrimp (Alpheus rubromaculatus). Photo: A. Stern, M. Levin

136

Gobies and other small fishes

In addition to the Gobiidae, many colorful small- and medium-size fish of various families (Pseudochromidae, Grammistidae, Nemipteridae) preside over the Eilat underwater vista. Some are shown here.

Small and beautiful: Orchid Dottyback (Pseudochromis fridmani), colored a fluorescent lilac-violet, which inhabits caves and shaded crevices, was first discovered in Eilat and named after David Fridman, the first curator of the “Coral World” Aquarium. Another small fish, Citron Goby (Gobiodon citrinus) inhabits branched corals. Yellowface Soapfish (Diploprion drachi), Common Soapfish (Grammistes sexlineatus), Frontal view of a Comet Longfin (Calloplesiops altivelis) in a typical “fright posture” in which the fish’ long tail mimics the shape of a moray eel peeping out from its shelter; a common Eyebar Goby (Gnatholepis anjerensis), Speckled Sandperch (Parapercis hexophthalma) which inhabits the sandy lagoon, and a Spinecheek (Scolopsis ghanam). Photo: M. Levin, J. Dafni, A. Diamant, B. Tamir

137

Surgeonfishes

Surgeonfish and Unicornfishes

A school of Brown Surgeonfish (Acanthurus nigrofuscus), and a solitary Sohal Surgeonfish (A. sohal). Photo: M. Levin, J. Dafni

More surgeonfish, and unicornfish: Sailfin Tang (Zebrasoma desjardinii), adult and juvenile (inset), Blackbarred Surgeonfish (Acanthurus gahhm) and Yellowtail Tang (Zebrasoma xanthurus), Bluespine Unicornfish (Naso unicornis) and the spike-less Orangespine Unicornfish (N. lituratus). Photo: B. Tamir, J. Dafni, E. Halevi, M. Levin

The family of surgeonfishes, Acanthuridae includes ten species in the Gulf of Aqaba, all herbivorous, grazing and browsing algae with their specialized teeth. Fish of this family are distinguished by a pair of erectable spines, sharp like a surgical lancet in the caudal peduncle, in some species it is highlighted by a striking warning color pattern. Brown surgeonfish schools roam the reef and lagoon, grazing the short algae. Sohal surgeonfish’ feeding tactics are different – it is a solitary territorial fish, violently defending its plot. Brown surgeonfish are also famous for their reproductive behavior, first observed in Eilat. At sunset, they gather in large schools; whence groups of several males and females rush to the surface, simultaneously releasing jets of eggs and sperm into the open sea.

138

Unicornfishes differ from surgeonfishes in two aspects: they have two pairs of fixed bony tapering plates instead of one pair of erectable spines, and a grotesque shorter or longer spike protruding from their foreheads. They are mainly browsers, feeding on leafy brown seaweeds. Some species turned to zooplankton feeding.

139

Rabbitfishes

Sea Breams and Spadefish

Rabbitfishes, of the family Siganidae, are also herbivores, seen frequently in seaweed-covered shallow lagoons. The most common species, Rivulated rabbitfish and Squaretailed rabbitfish live in larger schools, whereas the exquisite Stellate rabbitfish are seen mainly in pairs traveling across the reef. Rabbitfish are known for the poisonous sharp spines fixed at the end of their pelvic fins, and a hidden frontal dorsal spine that, unlike in other fish, is pointed forwards – inflicting a painful sting when carelessly handled. They also change their color pattern quickly to match the vegetation, an effective measure against predators.

The Seabream, family Sparidae, is a prized edible fish. The beautiful Twobar bream is their only representative in Eilat’s reef environment. Other edible species of this family are less conspicuous, and found in too small quantities to sustain commercial fishing. Mariculture practiced for 20 years in floating cages off the northern shore of Eilat, was centered mainly on the Gilthead bream, an introduced Mediterranean fish, that went wild and spread also to the reef environment. The related Spadefish (or batfish), of the Ephippidae, is vertically exaggerated, and often mistaken as butterflyfish.

Squaretail Rabbitfish (Siganus luridus) school and an individual, bearing camouflage colors (inset), and a pair of Stellate Rabbitfish (S. stellatus). Photo: J. Dafni, B. Levi, M. Levin

Twobar Bream (Acanthopagrus bifasciatus) the common natural seabream in Eilat. Fugitive Gilthead Breams (Sparus auratus) from the fish farms off the northern shore are found throughout the entire area. Circular Spadefish (Platax orbicularis), known also as Batfish, infrequently appears in larger schools. Photo: J. Dafni, M. Levin

140

141

Nocturnal fishes

Keeping the bed warm…

Nocturnal fishes. Cardinal fish: Black-ringed Cardinal (Apogon annularis) and Fiveline Cardinal (Cheilodipterus quinquelineatus) in a mixed school with Goldstriped Cardinalfish. Soldierfish: White-edged Soldierfish (Myripristis murdjan), Crown Squirrelfishes (Sargocentron diadema) school during the day and a solitary fish at night, hiding beneath a massive coral with extended tentacles and lastly, the Bigeye (Priacanthus hamrur). Photo: J. Dafni, M. Levin

Nocturnal (White-edged soldierfish) and diurnally-active fishes (Basslets) meet in the reef corner just before changing shifts. Photo: J. Dafni

When diving at night, the light torch reveals myriad of small plankton organisms, that rise to the surface at night, but relatively few fish predators to feed on them. Most nocturnal fish are small solitary plankton feeders as well as their medium size predators. During the day they assemble, seeking shelter in caves and crevices. Most of them have large eyes, adapted for night vision, and are red-colored or translucent. At night, when you point your flashlight at a cardinal fish (Apogonidae), a pearly luster is reflected back to you due to a layer of light-reflecting guanine crystals in its skin. Other nocturnal fish families are the Soldierfishes (Holocentridae) and Bigeyes (Priacanthidae) , most of which are red colored with patterns of white or dark lines and patches.

142

143

Sweepers

Two species of sweepers, nocturnal plankton-feeding fishes of the family Pempheridae are met diurnally in Eilat reef knolls and caves, the larger Cave sweeper and the smaller Pigmy sweeper. Both form dense population: the former is yellow-green and iridescent, changes colors according to the angle from which the fish is viewed whereas the almost transparent latter species justly earned its popular nickname ‘glass fish’.

Above: The Cave Sweeper (Pempheris vanicolensis) is a nocturnal plankton-feeder, spending the daylight hours in large schools in large caves or crevices. Below: Dense schools of Pigmy Sweeper (Parapriacanthus guentheri). They inhabit Moses Rock, the most popular coral knoll in the Eilat Nature Reserve (see also page 173). Photo: J. Dafni, Y. Aharoni

144

Life in the Current

Although the reef is economically self-sustained, there is an energy trade-off between the corals and the surrounding sea. The reef exports nutritious substances secreted by the corals onto the sea, while an influx of plankton, nourished by this contribution is harvested by many fish and invertebrates of the reef. Planktonic organisms are carried along by currents that brush the reef edge. Small fish, living at the reef edge or in offshore reef knolls venture out towards the incoming current to feed. It is evident that without the plankton, the reef ecology would be less rich and diverse. Larger predators lurk in the background, eager to enjoy this bounty.

Small reef fishes, Basslets (Pseudanthias squamipinnis), Green Chromis (Chromis viridis), Miry’s Damsel (Neopomacentrus miryae) face the incoming current. The normal current off Eilat’s shore moves in a southerly direction. When the currents shift around the fishes head in the other direction. Below: A school of Bicolor Puller (Chromis dimidiata) and a Striped Butterflyfish (Chaetodon fasciatus) Photo: M. Levin, J. Dafni

145

Triggerfishes

Filefishes

Triggerfishes (family Balistidae) have round, laterally flat bodies. Among the anterior dorsal fins the frontal fin spines are erectile: the first spine locks its position, and the second unlocks it (hence the name triggerfish). This and a similar erectile ventral spine prevent predators from swallowing them or pulling them out of hiding crevices. At least six triggerfish species live in Eilat. Picasso fish is the most colorful, and the largest of its family is the Blue triggerfish. The latter is a main predator of sea urchins. A pointed mouth and very thick skin protect it from the stinging sea urchin’s spines.

Members of the family Monacanthidae are related to the Balistidae. Their ‘trigger’, i.e. the second dorsal spine, is short, internally hidden and activated by muscles, and only one erectile spine shows, hence the scientific name “one spined”. A large species with vivid colors is the Scribbled leatherjacket. The Unicorn leatherjacket is a rare species, and it is the first record of this fish in Eilat. Honeycomb filefish is an attractive filefish with a pale or vivid color pattern.

Triggerfish variety: Bluethroat Triggerfish (Sufflamen albicaudatus); Red Sea Picasso fish (Rhinecanthus assasi), Adult and juvenile (inset); Yellowmargin triggerfish (Pseudobalistes flavimarginatus); and Blue triggerfish (P. fuscus), in the process of eating a long-spined sea urchin. (See also page 91). Photo: J. Dafni, M. Levin

Scribbled Leatherjacket (Aluterus scriptus) in an upright position and swimming; Unicorn Leatherjacket (A. monoceros) and below: the Honeycomb Filefish (Cantherinus pardalis) in two color variants, and three unidentified filefish. Photo: Y. Aharoni, M. Levin, D. Weinberg

146

147

Trunkfishes

Porcupine fish

Thornback Trunkfish (Tetrosomus gibbosus) sub-adult, Cubefish (Ostracion cubicus), newly born juvenile (‘dicefish’), a sub-adult and adult, Bluetail Trunkfish (Ostracion cyanurus) sub-adult and adult. Photo: J. Dafni, M. Levin

Two Porcupine fishes: Yellow spotted Burrfish (Cyclomycterus spilostylus), normal and inflated state (inset); Long-spine Porcupinefish (Diodon hystrix). Photo: J. Dafni, A. Colorni, B. Tamir

The bodies of Ostracionid fish are solid, encased in a triangular or quadrangle bony carapace, formed by fusion of the plate-like scales. Only the fins and tail are free to waggle. Members of this family come in a variety of colors, and are notable for the hexagonal or “honeycomb” patterns in their skin and dermal outer skeletons. Two common Eilati species are the Cube trunkfish and Thornback trunkfish, the former common both on the coral reef and in sandy habitats, while the latter – being well camouflaged - mostly roams the lagoon flats. In spring many minute black dotted yellow ‘dicefish’ are seen among sea urchin spines. They are the juvenile Cube trunkfish. A close relative, Blue-tail trunkfish is less common.

148

Tetraodontiformes is a taxonomical division, grouping members of three families: Trunkfish, Pufferfish and Porcupinefish. The last two are known also as blowfish because they are able to inflate their bodies by swallowing water for protection, more than doubling their size. The porcupine fish, Diodontidae further enhances this characteristic by being armed with short or long erectile spines covering their entire body. They are also equipped with a beak-like jaw, obtained by fusing all the teeth in each jaw to sharp plates, which they use to crush shells of mollusks and sea urchin. Their jaw is made of two ‘teeth’ (hence the scientific name, ‘two teeth’). Like the other fishes of the order Tetraodontiformes, their skin is poisonous, another protecting measure.

149

Pufferfishes

Tobies

Two Pufferfish: Masked Puffer (Arothron diadematus), and a Stellate Puffer (A. stellatus). Photo: J. Dafni, M. Levin

Crowned Toby (Canthigaster coronata), Pearl Toby (C. margaritata) and Red Sea Minipuffer (Torquigener flavimaculosus). Photo: J. Dafni

Another family of blowfish, closely related to the porcupine fish, is the Tetradontidae (=four teeth). Similarly, they have their teeth fused into plates, although with a distinct line of division (which ‘doubles’ their number). Another difference: they lack the porcupinefish long spines. Instead, their almost sandpaper-like skin carries minute spines. They are even more poisonous than other relatives: their inner organs contain a deadly poison called Tetradotoxin which may cause death in very low concentrations. Nevertheless, in Japan these fishes are processed by expert chefs and served in restaurants as a dish called Fugu, as kind of “Japanese roulette”.

150

These two Tobies are also Tetradontids, although they are smaller and their blowing capacity is much less effective than that of their blowfish relatives. They share other characteristics, such as a long snout and being poisonous. The third, named Red Sea Minipuffer, is a typical lagoon inhabitant.

151

Frogfishes

On the Sand and beneath

Two of the most common frogfishes of Eilat: Freckled Anglerfish (Antennarius coccineus); and below, the variable colored Spotfin Anglerfish (A. nummifer). Photo: M. Levin, Y. Aharoni

A Razorfish (Xyrichthys pavo) joins a Goatfish (Parupeneus cf. heptataenia) digging out sand dwelling worms or crustaceans. Inset: a juvenile X. pavo; Lizardfish (Synodus variegatus) in ambush and in the process of swallowing a damselfish, Green Chromis (Chromis viridis) (see page 122). Photo: M. Levin, J. Dafni

Frogfishes, family Antennariidae, are highly specialized benthic fishes. They have three extended dorsal fin spines on their heads, the frontal of which is modified into a fishing lure carrying a small worm-like ‘bait’ to attract small fish prey. They are well camouflaged, colors change, in adaptation to their background. They also show a unique ‘walking’ and ‘climbing’ motion, enabled by elbow-like joints in their pectoral and ventral fins.

152

Living on sand means digging, and this is what razorfishes do best. Their laterally compressed forehead enables them to penetrate the sand at the blink of an eye. Here one follows a goatfish. Below, a lizardfish digs in to ambush and catches a green damselfish that strayed from the reef.

153

Sea Turtles

Whales: Dolphins and kin

Sea turtles, descendents of terrestrial reptiles who went to sea many millions of year ago, are the only strictly marine reptiles now alive. Nevertheless they maintain their link with the non-marine environment in two ways: they breathe air and the female has to climb to the shore to lay her eggs in the wet sand. Interestingly, the sex of sea turtle babies is determined by the temperature in their nest. Of the three species in the Red Sea, the vegetarian Green turtle is the most regularly encountered by divers at Eilat. The Hawkbill turtle is rare, easily distinguished by its sharp, curving beak and tiled dorsal scales. It feeds on sponges and other reef sedentary animals, but juveniles eat plankton. Throughout the world sea turtles are considered endangered species. They are hunted, and their eggs taken by nest-robbers. Turtles are fond of jellyfish, and are quite often tempted to swallow pieces of plastic bags, leading to intestinal blockage and possible death. Several turtles in the “Coral World Park” in Eilat lay eggs every year in an artificial sand hatchery, and their offspring are released to reinforce the natural population. Eilat’s shore is mainly covered with coarse rock debris, not ideal for sea turtle nesting. Nevertheless, in 2007 one female Green turtle laid her eggs in the Nature Reserve beach. Baby turtles emerged after two months and ran into the sea. Special measures are taken to keep the beach dark at night to preserve an environment fit for nesting sea turtles.

Whales, the order Cetacea, are marine mammal predators. The large cetaceans, plankton-feeding baleen whales, are absent from the Red Sea, the smaller ones, of the family Delphinidae, better known as dolphins, are common. The most common one is the Bottlenose dolphin (Tursiops adduncus), whose natural schools swim freely in the Gulf. Less common are the open-sea Pantropical spotted dolphins. They are spotted mainly far from shore. Both are small dolphins, 2-2.5 m long. Still rarer is the dark-colored False killer whale, a relative of the oceanic killer whale (Orca). The “Dolphin Reef” inhabitants are Mediterranean bottlenose dolphins (T. truncatus), imported from the Black Sea. They are larger than the local species, reaching the length of 4 m. The “Dolphin Reef” trainers dedicate considerable time and effort to monitor the wild dolphins in the Gulf. Most of the lonely dolphins in Eilat’s vicinity are named and observed by them. The female Holly left her natural school and lived for several years next to a Bedouin village, maintaining close relations with a blind fisherman in Nuweiba, Sinai, and was a tourist attraction for years. She used to swim with the Dolphin Reef’s dolphins outside their enclosure. She was killed by fishermen. Three of her cubs, born separately, died also during the last decade, in unexplained circumstances. Marco is a juvenile bottlenose dolphin, whose mother died in unknown circumstances in Aqaba several years ago, and he became attached to divers at Eilat.

Hawkbill Sea Turtle (Erethmochelys imbricata): Above, juvenile and below a typical adult move across the deeper lagoon. Photo: M. Levin

Dolphins in Eilat: False Killer Whale (Pseudorca crassidens), Spotted Dolphin (Stenella attenuata) and a small school of Red Sea Bottlenose Dolphins (Tursiops adduncus). Photo: O. Armosa

154

155

Moderating the Human impact

Human influence on the sea is inevitable. Technology and human activity cause stress and kill sea animals. It is our duty to do everything possible so that our encounters and interactions with these organisms will be as tolerable as possible, even at the price of our own convenience. We have to protect the marine environment from evil-doers, either purposeful or unintentional. The seascape may include man, but his activity and footprints should disturb its welfare as little as possible. We shall present here some aspects of these activities. 10. Shipwrecks as diving sites 1.What is species diversity? 11. Underwater photography 2. Pollution: definition and pollution types 12. Diving sites in Eilat 3. Coral predation under ecological stress 13. Eilat Coral Nature Reserve 4. Coral settlement on artificial substrates 14. Coral World Underwater Observatory 5. Abandoned structures – what is their fate? 15. Dolphin Reef Resort 6. Species disappearance and reappearance 16. Underwater restaurant 7. Coral nurseries 17. Educational Nature Reserve 8. “Tamar” artificial reef 9. Diving and underwater activities

Diversity: the variety of species in a sample, community, or area. In these pictures two reef patches are shown, the upper showing a high diversity of small coral colonies of different species, whereas the lower picture shows large colonies of 1-2 species, and low variety of smaller colonies, i.e. Low diversity. Photo: J. Dafni

High Diversity

Low Diversity

A Rusty Parrotfish (Scarus ferrugineus) seeks shelter at night inside a boat wreck, adorned by ahermatypic colorful corals. The ambiguous attitude towards artificial objects is enhanced by the potential shelter it provides for certain reef fishes. Photo: M. Levin

156

157

Pollution

Definition: an undesirable state of the natural environment being contaminated with harmful substances as a consequence of human action. Types of pollution • Chemical pollution: introduction of chemical contaminants into a water body. • Terrestrial waste pollution: waste dumping into the water, e.g. garbage, sewage. • Thermal pollution: introduction of heated water into the sea. This reduces oxygen and causes thermal stresses in animals. • Genetic pollution: influx of genetically engineered living materials. • Introduction of exotic creatures that may replace or change the original fauna and flora. • Euthrophication: enrichment resulting from chemical input of excessive nutrients, resulting in excessive algal growth. • Noise disturbances: noise that may interfere with communication of natural organisms. Marine mammals are highly affected by this disturbance. • Light disturbances: artificial change in the light regime that may affect the natural diel periodicities (e.g. sea turtle hatchlings failing to navigate to the sea). • Physical damage to reefs and other habitats (breakage of corals, etc.).

Coral Predation

Like any other animal, corals are threatened by many predators. Some, such as small gastropods, seastars and butterflyfishes consume the living tissue, whereas others, such as parrotfishes and pufferfishes, break off pieces of coral to extract the living tissue and the symbiotic algae within. It is known that pollution promotes the survival of undesirable predators or parasites that are otherwise kept in low numbers. In a polluted site on the northern shore of Eilat an outbreak of Drupella, a predator snail of branched corals, was observed during the early 2000’s. Hundreds of snails attacked all types of corals there and killed them. Another corallivorous snail, Coralliophila, which attacks only the coral Porites, was also abundant there. An alternative explanation – that wrasses, known predators of these snails, were missing, and thus the snails grew unchecked – was also suggested to explain this phenomenon. A later visit showed that indeed, all the corals there died, and the snails disappeared along with the corals. The Crown-of-thorns sea star, a known coral predator, also increases its populations in disturbed reefs.

The different types of pollution affect organisms in many ways. They reduce their resistance to disease or parasitism, and cause their demise. Generally, a pollution-free coral reef environment has a high diversity of corals and accompanying invertebrates and fish, which translates into attractiveness to divers and beneficial revenue to the local community. A special effort is being made to facilitate access of a wide range of visitors to the reef in the form of an underwater observatory, coral reef nature reserves – while imposing strict rules and excluding divers from some areas. Divers who earlier complained of these rules and exclusions are beginning to cooperate, and the damage done by them seems to be decreasing. The entire human community will benefit as a result. Different pollution factors were discovered throughout the last decades that caused a notable decrease in biological diversity: Oil pollution from oil port and marine tankers, phosphate pollution, from both Eilat and Aqaba ports, sewage spills and other pollution sources. Several of these sources were reduced, but the danger that is caused by the urbanization processes and coastal development is still imminent. Only public awareness and consistent treatment of most threats will ensure the prosperity of this underwater habitat.

Effects of chemical pollution on reef inhabitants: two types of skeletal deformities in the Shortspine Velvet Urchin (Tripneustes gratilla elatensis) from the northern beach; “Goggle eyes” in the White-Edged Soldierfish (Myripristis murdjan). It is uncertain whether pollution or maltreatment is responsible for this last deformity. Photo: J. Dafni

158

Coral predators: Coral Predating Snails (Drupella cornus), gather to devour a Brain Coral (Platygyra), Corallivorous Snail, (Coralliophila neritoides), crowded on a Boulder Coral (Porites lutea) (Inset shows the typical violet aperture of the snail), a Crown-of-thorns Sea Star (Acanthaster planci) and Threadfin Butterflyfish (Chaetodon auriga) consuming stony coral polyps. Photo: J. Dafni, M. Levin

159

Artificial reefs

Introducing artificial substrates that may be populated by marine sedentary organisms will encourage the increase of fish and invertebrate populations to compensate for over-exploitation of the natural reefs. In general, artificial reefs will increase the carrying capacity for fish and invertebrates in the northern Gulf of Aqaba that otherwise is considered a “blue desert”. Some of these artificial reefs may be attractive targets for divers, helping to reduce the density of divers on the natural reefs.

Iron pilings of piers and marine scaffolding are covered with soft corals, sponges and ascidians, and is rapidly populated by fish and other reef organisms, practically becoming artificial reefs. Inset: A Broccoli coral (Dendronephthya sp.) hanging from an iron beam. Photo: M. Levin

160

Artifacts – take them or leave them

Objects such as this raise a dilemma: to remove these artificial objects, justly termed terrestrial waste, or leave them unchanged. Artificial objects may however provide hiding places for juvenile fishes, spawning sites for cuttlefishes or daylight refuge for nocturnal fishes.

A pipe sticking out of the sand has become covered with the Encrusting Soft Coral (Rhytisma sp.) and the Clownfish Anemone (Entacmea quadricolor) along with its symbiotic Clownfish (Amphiprion bicinctus). Photo: J. Dafni

161

Hoist a thrown stone…

Man-made Structures as habitat

An old proverb says “One fool throws a stone in the well and a thousand wise men can’t retrieve it” Artificial objects thrown into the sea many years ago pose another dilemma: in taking those out you may cause damage to the environment, but leaving them in is equally wrong. The solution may be to try to bury them beneath artificial reef components – broken coral boulders, transplanted corals, etc. Some of these artifacts attract divers.

The main sedentary organisms that settle on metal objects in the sea are soft corals, sponges and tunicates. The question why some materials and surfaces are unattractive to both coral types is a commendable topic for research and experiments. An artificial reef is defined as “a man-made, underwater structure, typically built for the purpose of promoting marine life in areas of generally featureless bottom.”

Nothing more to say. Photo: J. Dafni, M. Levin

Even the repulsive appearance of an underwater garbage dump such as this holds some promise for a pair of Red Sea Bannerfishes (Heniochus intermedius), attracted to the soft corals that overgrow the iron objects. Photo: M. Levin

162

163

Faunal fluctuations, they come and go…

Long term observations on the distribution of mollusks and other invertebrates show great fluctuations of many species, from abundance to near decimation. These fluctuations are partly natural occurrences and partly the result of pollution.

Mollusks and crabs that underwent extreme fluctuations observed in a long term study. Above: Trush cowry (Erosaria turdus), covering its shell with its polishing mantle, replaced the Twin-blotched Cowry (Erosaria nebrites) that was common during the 1980’s; Land hermit crab (Coenobita scaveola), a nocturnal beach prowler, that hides during the day under rocks or among rubble. Once common, Sea harp, (Harpa amouretta) entirely disappeared. Bottom: once common, now rare or gone (left and clockwise): Strombus mutabilis, Gibberulus gibberulus, Erosaria nebrites, Casmaria ponderosa, Bursa grannularis, Murex ramosus, Terebra maculata, Modiolus auriculatus, Laevichlamys superficialis, Cardites rufa and Tellinella virgata. Photo: J. Dafni

164

Coral Nurseries

The natural recovery of coral reefs may take many years. The damage to natural coral reefs across the tropics in the wake of the 2004 tsunami accentuated the need for an alternative “gardening” technique to rehabilitate denuded reefs. A nursery component in an active reef restoration program is a tool that provides coral source material for the rehabilitation of denuded reef areas. Here, a mid-water floating coral nursery is presented, an improved prototype of earlier attached-to-substrate coral nurseries off Eilat’s northern shore. Thousands of fragments from colonies of branching and massive species were grown on an artificial substrate at a six-meter depth, 14 meters above the sea floor, close to fish-farming facilities in this area. Total mortality of fragments during 10 nursery months was very low (less than 10%) while growth rates were high (up to 6-fold in height). At that depth the nursery gets sufficient light and does not interfere with recreational activities. Mariculture procedures include removing sediments and protection against corallivorous organisms.

A coral nursery off the northern shore of Eilat is suspended on a net, 14 m above the sea floor. Photo: S. Shafir

165

“Tamar” Artificial reef

Based on the observations mentioned above, and considering the various factors that may determine the preferable materials and spatial morphology for an artificial structure, an experimental artificial reef has been erected, and a study devised, which will answer the following questions:

“Tamar” Artificial reef

• Will this structure have an effect on the local environment? • Will fish and other (non coral) invertebrates accept it and settle into it? • Will it contribute to increase the carrying capacity of the natural reef? • Will the coral community settled on it be stable? • Will divers find it a desirable location? • And finally, can it be used to lure divers away from natural reefs and onto artificial locations? This research is carried out by Ben-Gurion University of the Negev, Eilat Campus in cooperation with the Authority of Nature Protection and financed by the USAID-MERC and Whitely Foundation, as a joint Israeli-Jordanian project. The local coordinator of the program is Dr. N. Shashar. The Interuniversity Institute and the National Center for Mariculture provide scientific support. The “Tamar” concrete artificial reef was constructed by the Israeli company OBS, and sunk on an offshore sand flat in the Eilat Nature Reserve in April 2007. Five months later, coral fragments (nubbins) of several species were transplanted from a nursery into prefabricated holes in the concrete structure. Preliminary results look promising - coral fragments have adapted to the substrate and fish are already attracted to the new environment.

Eleven coral species were transplanted in the project; in situ fragment batch. Photo: S. Shafir

166

The concrete and metal parts were prefabricated in the country’s center, brought to Eilat, sunk, and assembled in situ. Five months later coral fragments (inset) were transplanted into small holes in its surface. A Broomtail Wrasse shows interest in moving in. Photo: M. Levin, J. Dafni

167

Divers – what are they up to?

Eilat’s reefs accommodate a record number of divers. They support many diving clubs, hotels and local guides and provide the community with high revenue. Yet their impact on the reef may be harmful: breaking corals, raising sand which settles on the corals, chasing fishes out of their shelters, and other undesirable activities. Measures taken by the Nature Reserve Authority have started to show some results. Habitats that suffered serious damage have started to improve. Strict enforcement, combined with self-discipline on the divers’ side, encourages our belief that Eilat’s reefs will survive, and that the corals and divers will live together for many years to come. Photo: J. Dafni

Shipwrecks

Shipwrecks are the remains of ships sunk in storms or by hostile activity. Apart from their archaeological or historical importance, wrecks in shallow water turn out to be favorite diving sites. The cover of algae, sponges and colorful soft corals attracts fish and other marine organisms. Fortunately the coast of Eilat has not witnessed any marine disaster, but small and medium size ships have been deliberately sunk to increase the carrying capacity of the northern part of the Gulf for fish and to provide divers with picturesque diving sites. The best-known shipwreck in Eilat is the military vessel “Sufa”, a missile boat that served for 20 years protecting Israel’s Mediterranean shores. Its history is quite eventful. This was one of five naval boats that Israel bought from France in the early 1960’s. It was built in Cherbourg harbor, but after the Six-Day War in 1967, French President Charles de Gaulle declared an embargo on the sale of military equipment to Israel. Diplomatic efforts to free the boats failed, and on Christmas Eve, 1969, the Israeli missile boats - which had already been paid for - sneaked out of the harbor to the open sea and sailed to Israel. They were known as the “Boats of Cherbourg”. The long service of the “Sufa” ended in 1994, when it was purposely sunk off the coast of Eilat in 27 meters of water. Other naval boats like the “Yatush” were also sunk in the vicinity, and they have become an important co-production of technology and nature.

Divers survey the ship’s hull and growth of corals on deck and on the bridge structure of the “Sufa” wreck. Photo: M. Levin

168

169

Underwater photography

This is the modern form of hunting. Taking pictures in a non-destructive way is advantageous to nature in a variety of ways: it enhances awareness of sea life, provides data on animal behavior, and records problems developing in the natural environment. It might however be destructive if photographers encroach upon small fishes or slugs, disrupting their routine and endangering their very existence. Considerable effort should be invested in education and enforcing proper regulations to prevent damage by too enthusiastic photographers.

Diving sites in Eilat

The short, ca. 15-km long coast of Eilat offers the diver many diving sites. In this short account, based on the popular Hebrew Book “44 Diving Sites along Israel’s Coast,” we list here a dozen sites and point out the highlights of each and their maximal depths (according to safety regulations). The reader should consult one of the many local diving clubs for updated information on new attractions and for regulations and limitations concerning diving at these sites. A local diving “buddy” is highly recommended. The sites (from north to south) are: 1. The Pyramid: artificial reef and objects off the northern shore (depth up to 32 m) 2. Wadi “Dekel”: drowned wadi, reef and topographical views (up to 30 m) 3. “Dolphin Reef”: a private beach resort: reef, natural and artificial, diving with dolphins (<10 m) – entrance fee. Diving is only via the Dolphin Reef Club. 4. “Sufa” Wreck: known locally as “Satil” – a naval boat wreck (see page 169) (depth 27 m) 5. “Yatush” Wreck and Garden Eels: another small “wreck” and natural reefscape (depth 33 m) 6. Coral Beach Nature Reserve: a protected area. Includes Joshua and Moses Rocks. Entrance fee. Diving organized by Eilati clubs (depth 33 m). No night dives. 7. “Japanese Gardens”: a protected area. Entrance only by boats. Entrance fee. Diving organized by Eilat clubs (depth 30 m) 8. The “Caves”: opposite the Lighthouse. A shallow dive (depth 5 m). 9. “Veronica Shore” (shallow): shallow dive along the coast. Starting south of the Lighthouse (depth 6 m) 10. “Veronica Shore” (deep): deeper dive along the coast. Starting opposite Princess Hotel, diving northwards (depth 24 m) 11. “Princess Hotel” dives: deeper dive. Beautiful coral knolls. Entrance through the hotel’s southern seaward walkway. Closed at night (depth 25 m) 12. “Neptune’s Tables”: next to the Egyptian border is a large concentration of flat-topped branched corals, partly capsized. Entrance and exit from the Princess Hotel beach (down to 25 m)

Photo: M. Levin

Underwater photographer in action. Photo: M. Levin

170

Important notice: Along the Israeli Coast it is forbidden to dive solo. Diving with knives, sharp metal instruments or spear guns is prohibited. For safety reasons, it is forbidden to swim beyond the float line where the area is open to boat traffic. Diving below it is permitted. Along the southern shore, enter the sea via designated entrance points. Further information is available in the aboverecommended book (alas, only in Hebrew).

171

Eilat Coral Nature Reserve

Although the entire shore line of Eilat’s corals and coral reefs is protected, the official Coral Nature Reserve extends along a 1.5 km stretch of fenced beach (entrance fee required), and 3 km of open shore with free access. This is a preferred diving site.

A fringing reef along the shore of the Nature Reserve protects a narrow lagoon. Along the seaward drop of the front reef, coral colonies and patch reefs – the “Japanese Gardens” – continue to a depth of 50m and more (picture taken from the underwater observatory walkbridge). Inset: annual exposure of the reef flat due to extremely low tide. Photo: J. Dafni

Opposite page: the most impressive habitat of the Nature Reserve is the 8-10 m high Moses Rock. It is rich in plankton-feeding fish and colorful soft corals. In the shallow lagoons boulder corals and flat-topped branched corals (pp 44, 157) dominate, next to large giant clams (page 83). Photo: J. Dafni

172

173

Underwater Observatory Marine Park

In 1974 the first underwater observatory in the world came into being. A metal structure sunk into 10 m deep water of the Eilat Nature Coral Reserve offered in the first time direct observation into the domain of the corals and coral fish. From the viewpoint of nature conservation, it is a golden opportunity to introduce thousands of people to the underwater world without intervening with the ecological system. Through the windows and in the many aquaria in the park, hundreds of fish and invertebrate animals live in an almost natural habitat, since many of these animals enter the park as larvae in the seawater influx directly from the sea. The displayed corals, sea anemones, and many other sea organisms glow under the fluorescent light of the aquaria (next page), in a splendor that cannot be seen in nature. Rare fishes, and even common ones, shy to the human observer, like the Flashlight fish, live in total darkness and flicker with their light-emitting organ to lure small prey to their mouth. In special aquaria, juvenile fishes of extreme beauty are displayed. Educational programs carried out by the “Coral World” team for local k-6 pupils rehabilitate broken corals and facilitate sea turtle and seahorse reproduction for their later release to the sea. A visit to the park is a must, even for the experienced diver.

The underwater observatory; Panoramic view of the “Eilat reef” circular Aquarium; Exquisite corals and fish display in the aquaria department. Photo: J. Dafni

174

Where else…

Where else would you meet a curious parrot fish looking at you from close distance without getting wet or alarming the fish? Where else would you see a large variety of reef fishes that call this artificial metal framework home? Where else can you see living corals at full size, glowing mysteriously in eerie light conditions?

Under artificial illumination applied in the Coral World aquaria the proteins in the coral tissues and their symbiotic algae glow. The scientific explanation is that only part of the ultraviolet light energy is absorbed by the coral or its symbiotic algae, and the remaining energy is emitted as light in the visible spectrum. This phenomenon cannot be seen in nature. Photo: J. Dafni

175

The “Dolphin Reef”

Underwater Restaurant

Above: Diver and instructor on an introductory dive with a dolphin. Below right: A white soft coral growing on the fence bordering the dolphins’ enclosure next to the public swimming area. View from the reef knoll of Black Ascidian and Basslets; and a beautiful camouflaged Tunicate (Halocynthia sp.). Photo: J. Dafni

A walk-bridge connects the underwater restaurant with the shore, artificial reef teeming with colorful coral fish, and a fish school gathering at the restaurant windows. Photo: J. Dafni, M. Levin

The Dolphin Reef is a recreational site that includes an enclosed public swimming area and a wide space for a school of captive bottlenose dolphins. The dolphins are treated by the trainers with respect and trust as they carry on their normal daily routine of feeding, breeding and playing. Small reef patches and the fence between the two areas are populated by many invertebrates and fish. The main attraction of this site is the opportunity to dive with the dolphins in a natural coral reef combined with an artificial reef. Visitors can walk along a floating bridge to the dolphins’ area to watch them. I personally enjoy snorkeling along the net fence bordering the dolphins’ enclosure, next to the public beach with its supple growth of corals and colorful fouling organisms.

176

It is a very unusual restaurant in that it is located underwater, 5 m below sea level in the vicinity of the Um-Rashrash site (overleaf). It is surrounded by windows facing an artificial reef, rich with soft corals, sponges and fish. Through the windows a vivid panorama appears during the day, shifting at night to a ghostly vision of diurnally active fish taking shelter among the corals while nocturnal predators emerge from the dark, approaching and peeping through the windows.

177

Educational Coral Reserve “Um-Rashrash Reef”

On March 10, 1949 the first IDF soldiers arrived in Eilat in a military operation that concluded the War of Independence. Upon reaching the shore they found several mud huts and a Godforsaken police station named Um-Rashrash, and hoisted the now-famous “ink flag”. On the beach opposite Um-Rashrash (presently a memorial site) they had their first experience with Red Sea marine life in the form of sea urchin spines. The small coral reef, said to be the northernmost coral reef in the world, has survived all events since and is now one of Eilat’s swimming beaches. Lately a plan has been initiated to make this reef an Educational Coral Reserve. On the reef and in the adjacent lagoon and intertidal zone, more than 50 coral species and over 100 fish and invertebrate species have been recorded. Many of them appear in this book.

Um-Rashrash Reef, General view: Pajama Slug (Chromodoris quadricolor), Brain Coral (Platygyra sp.) and a giant Boulder coral (Porites sp.). Photo: J. Dafni.

178

The programmed activities in the Educational Reserve include guided swims and dives, studying the natural habitat, and individual student learning projects. Being a public beach with all necessary facilities and an easy approach to the reef and other habitats assures coexistence between nature and human activities. Only wise and sustainable development will preserve this natural habitat.

Some of the Reserve inhabitants: juvenile Lionfish (Pterois miles), a large colony of Plate Coral (Turbinaria), a slightly damaged very large Lobed Coral (Lobophyllia corymbosa), and an Anemone Carrier Hermit Crab (Dardanus tinctor). Photo: J. Dafni, I. Ben-Tov.

179

Eilat Coral reefs in the 21st century

Can we return to the pristine 1960’s? Probably not, but we can preserve seawater quality and protect the remaining coral reefs. Furthermore, artificial reefs and structures like the one illustrated below can serve as substrate for corals and their accompanying fauna, preserving Eilat’s underwater environment as a tourist attraction for ages to come.

Eilat 2006

How will Eilat’s coral reef fare at the mid-21st century?

Throughout the world, coral reefs will be in constant danger emanating from climate change. Global warming and environmental pollution have already affected coral reefs throughout the tropics. The same may well apply to our coral reefs, which are dangerously close to a commercial harbor, industrial facilities and urban and recreation centers. The human population density poses a dilemma - whether to turn the reef into a backdoor coral garden, or set a limit to the extent of human exploitation by visitors and divers at all costs. How can we both “have our cake and eat it, too?” Eilat’s coral reef is too dear to let it be neglected or mistreated. Its exploitation must use sustainable development principles that will ensure that this natural resource will not fall victim to developers’ zeal. It is well known that fish and invertebrate behavior is strongly affected by human intervention. A group of several divers mobbing a small seahorse, slug or octopus interferes with their routine activity, causing them long-lasting trauma. Therefore I want to put forward several ideas that may enable large crowds to enjoy the encounter with coral reef life without placing an extra burden on the environment. One option is the use of high technology to spare marine organisms from human-inflicted damage: 1. Creating hiding places for divers to approach and observe marine organisms without interfering with their natural habits. They can be included in the design of artificial reefs, enabling divers to witness extraordinary activities in situ, such as the Eel gardens, shipwrecks etc. 2. Placing tele-operated cameras at ‘strategic’ points in the reef environment or on board unmanned submarines and relay audiovisual material to an auditorium ashore. The aim is to show it to the public in real time, instead of their swimming onto the reef. The relay can be used also as database material or in research. 3. Photographed footage can be sold to visitors or broadcasted. 4. A submarine sculpture garden, created by skilled artists on underwater shallow sand flats, empty of corals, will attract divers both for its artistic value as well as for the combination of corals and other sedentary organism attached to it. Such artificial reefs are much more valuable and attractive than ordinary artificial reefs. It should be built from durable noncorrosive materials satisfying technical and safety specifications. 5. An electronic database of the animals and plants on the reef, available to the public, will be (a) an identification aid, (b) a checklist for the presence/absence of living organisms, and (c) a basis for long term monitoring of the natural populations. 6. A periodical bulletin issued by local experts will increase awareness of the coral reef, and monitor seasonal and long-term changes.

Eilat 1966

The behavior of fish and marine invertebrates, especially the mutual relations between them are an important research topic that will keep many scientists busy in the future. Here, unexplained relationship between two fishes – parasitism, symbiotic relationship or what? – Yellow Goatfish (Parupeneus cyclostomus) and a female Bird Wrasse (Gomphosus coeruleus). Photo: J. Dafni

Photo: M. Levin Photo: J. Dafni

180

181

Endnotes

As the reader might have already noticed, the gallery of animals that take part in the ecological wonder of the reef is wide, and is still revealing new secrets – new kinds of animals, new ways of life, new insights. Eilat has its roots in the sea. The coral environment is its main attraction. Small as it is compared to the vast areas and long beaches of neighboring countries, Eilat offers a more qualitative approach to the sea. Three academic institutions practice marine biology and ecology in Eilat, and other educational institutions study its economical potential, and its preservation. The Underwater Observatory Marine Park is unique. It is not as spectacular as the huge aquaria and museums of the largest cities in the world, but it is connected to the sea. It is within a coral beach, and many of the smaller organisms inside its tanks came from the sea as larvae. The first underwater observatory was established in Eilat, an invention that enables visitors to meet eye-to-eye the free reef fishes that approach by their own choice, curious to meet the humans across the observatory window glass. This book displays only a small sample of the large variety of life forms revealed in the Eilat reef environment. Many more can be seen in the observatory and in the Park’s aquaria. Throughout the world, coral reefs are losing ground alarmingly. Pollution reduces their diversity; global seawater warming causes coral bleaching, a phenomenon of zooxanthellae expulsion from their coral host, leaving it to die, along with predation of corals by sea stars and other predators and coral diseases; and on top of the other plagues, there is the over-exploitation by fishermen and divers alike. Luckily, the Gulf of Aqaba (Eilat) is only slightly affected by these factors. The cooler water prevents bleaching, pollution is relatively mild, and other factors are - partly, at least - under control. Public support is vital to protect the reefs, to rehabilitate damaged habitats and to monitor and foresee any danger to this fragile ecosystem. As author I wish to acknowledge the help of many divers who trusted their photographs with me, especially those of the “Tapuz” website divers forum, who replaced the fishing rod with a camera: Y. Aharoni, O. Armosa, I. Ben-tov, R. Biran, M. Chen, R. Cohen, A. Colorni, L. Dafni, A. Diamant, Y. Esh, J. Grinfeld, A. Gur, E. Halevi, A. Kendler, R. Koslawsky, O. Lederman, B. Levi, K. Levy, A. Lynn, E. Meidan, Z. Movshowits, L. Pintchover, B. Tamir, S. Shafir, N. Shashar, M. Shpigel, A. Stern, D. Weinberg and D. Zakai. Special thanks are due to Michael Levin, whose observations and photographs broadened the book’s scope. Dr. Jeffrey Gansburg and Mr. Binyamin Koretz reviewed the English text, and their contribution is highly appreciated. To the organizations and individuals who supported the publishing of this book. To my family, who supported my old craving for unfolding the sea’s secrets. To my daughter, Lior Dafni, who designed and shaped the book. Jacob Dafni

182

Further Reading

Dafni. J. (1995) Eilat: Routes and trails in the Eilat Region. Gefen Publishing House, Jerusalem Dafni, J. (2000) Gulf of Eilat, from the Red Sea to the red line. Cherikover Publishing Company, Tel Aviv (Hebrew) Dafni, J. (2008) Eilat’s Coral Reefs, optimistic view. Yeela Publishing, Eilat (Hebrew) Debelius, H. (2001) Red Sea Reef Guide. IKAN, Frankfurt Dor, M. (1984). CLOFRES: Checklist of the Fishes of the Red Sea. Israel Academy of Sciences and Humanities, Jerusalem Edwards, A.J. & Head, S.M. (Eds.) (1987). Key Environments: Red Sea. Pergamon Press, Oxford Gur, A. (2004) MAPA’s Guide to Israel’s Best Diving Sites. MAPA Publ. Tel Aviv (Hebrew) Marco, S. (1988). The Geological History of Israel in light of Plate Tectonics. Eilat Field School Publication (Hebrew) Por, F. D. (1978). Lessepsian Migration: The Influx of Red Sea Biota into the Mediterranean by Way of the Suez Canal. Springer, Berlin Randall, J.E. (1983) . Red Sea Reef Fishes. 192 pp. Immel Publ. Co., London Reiss, Z. & Hottinger, L. (1984). The Gulf of Aqaba: Ecological Micropaleontology. Ecological Studies no. 50. Springer, Berlin Richmond, M. D. (ed.) (1997) A Guide to the Seashores of Eastern Africa and the Western Indian Ocean islands. Swedish International Development Cooperation Agency (Sida) Schuhmacher, H. (1976) Korallenriffe. BLV Germany Shpigel, M. (1997) Fishes of the Red Sea. Red Sea Magazine, Ra’anana, Israel Vine, P. (1996) Red Sea Invertebrates. Sea Challengers Publ. Co., London Yonow, N. (2008) Benthic Opisthobranchs of the Red Sea, Pensoft Publishers, Sofia

From the same author:

183

Glossary

Ahermatypic: non-reef-building corals. Alpha female: the individual dominant female in the community. Ampullae: medusa forming polyps in hydrozoans. Anal fin: the fin behind the fish anus. Anal: of the anus (= vent). Anthocaulus: Juvenile attached polyp of mushroom corals (pl. anthocauli). Aristotle’s lantern: mouth-apparatus of a sea urchin. Asexual: reproduction not involving the union of male and female germ cells. Atoll reef: circular or continuous barrier reef surrounding a lagoon. Atrial: of the atrium (in sea squirts). Autozooid: a fully developed polyp (in corals). Azooxanthellate: not having zooxanthellae, contrary to zooxanthellate. Baleen: in some whales, the comb-like fibrous plates hanging from the upper jaw, used to sieve food from sea water. Barbels: Whiskers like projections that help the fish locate food in the sand. Benthic: pertaining to the bottom of a sea, the Benthos. Bilateral symmetry: with left and right sides that are approximately mirror images. Bioherm: A rock structure built up by sedentary organisms, as corals, algae, mollusks (=reef) Blastula: ball-shaped first larval stage in multi-cellular organisms. Bleaching: discoloration of zooxanthellate corals, caused by the death or release of the symbiotic algae. Bogus eyespot: eye-shaped color pattern, aimed to fool a predator. Browsing: feeding on higher vegetation- stems, leaves etc. Byssus: fibers issuing from between the valves of a bivalve for attachment. Calcareous: made of calcium carbonate, chalky. Calcareous algae: containing calcium carbonate, chalky. Carapace: In crustaceans, the part of the external skeleton that covers the cephalothorax. Carnivore: an animal that eats other animals. Cartilaginous: made of cartilage (as in sharks and rays). Caudal: of the tail. Cephalothorax: combined head and thorax in crabs and lobsters. Chela: a moveable lateral toe like the claws of a crab or lobster. Cheliped: in crustaceans, the first pair of legs which bear the chela (claws). Chlorophyll: green pigments in plants that facilitate photosynthesis. Choanocytes: collar cells – flagellae bearing cells in sponges. Cirri (fish): fin spines splitting to tassel-like filaments. Also finger-like clinging processions in the feather stars (Crinoids). Cleaning station: location where fish and other marine life congregate to be cleaned. Cnidocyte: The “stinging cell” of a cnidarian. Cnidosac: a sac of a nudibranch gastropod, containing undischarged cnidocysts. Commensal: “eating from the same table”- loose symbiotic relations. Corallite: skeleton produced by an individual polyp. Cuvierian tubules: defensive structures expelled through the anus of sea cucumbers. Dactylozooid: Stinging polyp in hydrozoans. Deuterostomia: major group within the animal kingdom, in which vertebrates included. Diel: a 24-hour period, usually encompassing one day and one night. Dorsal: pertaining to the back, or situated near to or on the back. Dorsoventral: axis between the dorsal and ventral sides. Endemic: confined to a country, sea or land. Endosymbiosis: relations, where the symbiont lives within his partner’s body. Ephyra: the earliest free-swimming stage of scyphozoan medusa. Epifauna: fauna living on the ground. Errantia: worms with a freely moving lifestyle. Eukaryotic: cells containing internal organelles, especially a cell nucleus. Euthrophication: excessive primary production due to enrichment in nutrients. Extratentacular: form of budding in hermatypic reef corals. Fauna: all the animal life in a particular region or period. Flagellum: whip-like organelle of the cell. (pl. flagellae). Flora: all the plants in a particular region or period. Forereef: seaward facing reef end. Fouling: organisms growing on submerged boats, artificial surfaces and piers. Fringing reef: reef fringing the shoreline in shallow depth. Gastrozoid: Eating polyp in hydrozoans. Gill covers: lid or flap covering the gill aperture in fish. Gill slits: slits or gill opening in cartilaginous fish. Grazing: feeding on low vegetation, such as grass. Guanine: one of the main nucleobases in DNA. Hectocotylus: arm of male cephalopods modified for fertilization. Herbivore: animal that eats only plant material.

184

Hermaphroditic: Having both male and female reproduction organs. Hermatypic: reef building corals, stony corals. High tide: high water level within the tidal range. Hydromedusa: medusa stage of hydrozoans. In situ: In its natural position or place. Intertidal: region between high and low tide. Intratentacular: polyp division in hermatypic reef corals. Irregularia: Sub-class in the Echinoidea showing bilateral symmetry. K-strategist: animal that grows slowly and lives longer. Larva: earliest stage of animals that undergo metamorphosis, differing from the adult (plural larvae). Lateral line: series of pore-like openings (to sensory canal) along the sides of a fish. Low tide: low water level within the tidal range. Mantle: an organ in mollusca, covering the body, secreting calcium carbonate to create a shell. Mariculture: marine aquaculture of fish and invertebrates. Medusa: free-swimming sexual stage of a coelenterate, such as a jellyfish. Mesogloea: Jelly-like middle layer in cnidaria. Monocotyledon: Any of various flowering plants, such as grasses having a single cotyledon. Nekton: collective name for active swimming organisms, such as fish, squids etc. Notochord: a long, flexible rod which runs the length of the back in animals belonging to the phylum Chordata. Nutrients: minerals needed for photosynthesis or life sustaining processes. Ontogeny: the development of an organism from egg to adult. Operculum: cover of a snail’s aperture, when it draws in. Oral: of the mouth. Oral arms: arms surrounding a jellyfish mouth Oscula (pl. of osculum): The mouth-like opening in a sponge, used to expel water. Ossicle: any small bone, embedded in soft tissue (Echinoderms). Ostia (pl. of ostium): any of the small openings or pores in a sponge. Pectoral fins: paired breast fins in fish. Peduncle: the fleshy area to which the caudal fin is attached. Pelvic fins: paired ventral fins in fish. Petaloid: flower-like in echinoids. Photosynthesis: process of turning CO2 to carbohydrate by plants. Pinnules: side branch structure on the tentacle of soft corals. Plankton: drifters, passive moving marine organisms. Planula: Larva of cnidarians (plural larvae). Proboscis: The elongated mouthparts, snout or beak. Prokaryotic: single-celled living organisms, not having cell nucleus. Protandrous: in sequential hermaphrodites, sex changing fish - male first Protogynous: in sequential hermaphrodites, sex changing fish - female first. Quaternary: Geological period starting at ca 2 million years ago to present. Rachis: axis or central line of a sea pen coral. Regularia: Sub-class in the Echinoidea showing circular symmetry. Rift: a place where the Earth’s crust and lithosphere are being pulled apart. r-strategist: animal that grows quickly and dies sooner than a K-strategist. Sedentaria: collective name for sedentary polychaete worms. Sexual dimorphism: organism in which both sexes are different in shape or color. Siphon: tube-like structure in clams or octopuses, for passage of seawater. Siphonozooid: specialized polyp in colonial soft corals, which functions as intake for water. Spicules: skeletal structures that occur in sponges and soft corals. Spongin: protein building the structure of most sponges. Spring bloom: seasonal abundance of algae, occurring in early spring. Spring tide: excessively high and low tides, occurring twice a month. Stolon: horizontal stem which grows along the surface. Strike-slip: in geology, fault involve motion which is parallel to the strike of the fault. Swim bladder: a gas-filled sac in fishes that provides buoyancy. Symbiotic: mutual positive relations (symbiosis) between two or more organisms. Tadpole stage: free-swimming larva of ascidians, with a tail like an amphibian. Test: a hard outer covering as of some amoebas and sea urchins . Tide: rising and falling of Earth’s ocean surface caused by forces of the Moon and the Sun. Transform rift: horizontal moving faults, such as in the Dead Sea Rift. Tubefeet: flexible tube-like locomotion and attachment systems in echinoderms. Valve: one shell of a clam, usually having two valves (shells attached at the hinge). Vascular: water and nutrient conductive tissue in plants. Ventral: of the belly, or lower side. Warning coloration: intended to make an organism more noticeable. Zooplankton: plankton consisted of animals. Zooxanthellae: unicellular yellow-brown algae living symbiotically in the tissues of corals.

185

Scientific Index

Abudefduf saxatilis 122 Abudefduf sexfasciatus 122 Acabaria cf. erythraea 66 Acabaria cf. pulchra. 66 Acabaria cf. splendens 66 Acanthaster planci 35 92 159 Acanthella carteri . 23 Acanthopagrus bifasciatus 141 Acanthopleura vaillantii 10 Acanthurus nigrofuscus 138 Acanthurus sohal 138 Acanthurus gahhm 139 Acropora cf. hyacinthus 35 40 43 51 52 Acropora sp. 46 47 123 159 166 Actinodiscus nummiformis 72 Actinopyga bannwarthii 96 97 Aeoliscus punctulatus 110 Aetobatus narinari 106 Alpheus djibutensis 136 Alpheus rubromaculatus 136 Alticus kirkii 135 Aluterus monoceros 147 Aluterus scriptus 147 Alveopora 35 59 Amphiprion bicinctus 17 70 123 161 Anampses meleagrides 124 Anella hicksoni 13 67 131 Antennarius coccineus 152 Antennarius nummifer 152 Anthelia 64 Antipatharia 56 Antipathes cf dichotoma 56 Apogon annularis 142 Apogon cyanosoma 135 Argonauta argo 85 Arothron diadematus 150 Arothron stellatus 150 Ascidia 89 100 176 Aspargopsis taxiformis 21 Aspidontus dussumieri 134 Asterina burtoni 92 93 Asthenosoma marisrubri 94 Astroboa nuda. 98 99 Astropecten polyacanthus. 17 Atheloperca rogaa 107 116 Aurelia aurita 26 Bodianus anthioides. 124 Bothus pantherinus 132 Botrylloides spp. 100 Brachiodontes pharaonis 164 Bursa granularis 164 Callechelys marmoratus 109 Calliactis polypus 70 Callispongia sp.. 98 Calloplesiops altivelis 137 Cantharellus 35 Cantharellus doederleini 38 Cantherinus pardalis 147 Canthigaster coronatus 151 Canthigaster margaritata 151 Cardites rufa 164 Carapus 96 Carpilius convexus 89

186

Casmaria ponderosa 94 95 164 Cassiopeia andromeda 26 Caulerpa serrulata 20 Cellana eucosmia 10 Cephalopholis miniatus 116 Ceratosoma magnifica 80 Cerianthus spp. 72 cf. Cladopsammia 55 Chaetodon auriga 118 119 159 Chaetodon austriacus 119 Chaetodon fasciatus 118 119 145 Chaetodon lineolatus 118 119 Chaetodon paucifasciata 118 119 Chaetodon semilarvatus 118 Chaetodon trifascialis 118 Cheilinus lunulatus 91 125 167 Cheilodipterus quinquelineatus 142 Cheilodipterus sp. 135 Chelonia mydas 154 Chicoreus ramosus 164 Choriaster granulatus 93 Chromis dimidiata 145 Chromis viridis 31 122 123 145 153 Chromodoris quadricolor 22 178 Chrysaora / Pelagia 27 Chrysiptera annulata 122 Cirrhitichthys oxycephalus 131 Cirripathes anguina 56 57 Cirripathes sp. 62 Cladiella 65 Cliona vastifica 22 Clypeaster humilis 91 94 102 Codium arabicum 21 Coenobita scaveola 174 Conus tessulatus 88 Coralliophyla neritoides 159 Coris aygula 102 124 Coris caudimacula 124 126 Corythoichthys schultzi 110 Crella cyathophora 23 Cryptocentrus steinitzi 136 Cryptodendrum adhesivum 71 Ctenactis echinata 38 39 Cyclomycterus spilostylus 149 95 Cynarina lacrymalis 38 Cynoglossus sinusarabici 133 Dardanus lagopus 88 Dardanus tinctor 16 179 Dascylus aruanus 122 123 Dascylus trimaculatus 122 126 Dendrochirus brachypterus 114 Dendronephthya sp. 60, 63 Dendropoma maxima 78 Diadema setosum 16 125 146 Dictyospaeria cavernosa 21 Diodon hystrix 149 Diploastrea heliopora 33 37 Diploprion drachi 137 Dromia sp. 89 Drupella cornus 159 Dunkerocampus multiannulata 111 Echeneis naucrates 19 106 Echidna nebulosa 108 Echinodiscus auritus 94 95

Echinopora 33 36 37 Echinopora forskaliana 37 Echinopora fruticulosa 37 Echinopora gemmacea 37 Echinothrix calamaris 94 Ecsenius gravieri 134 Engina mendicaria 77 Entacmea quadricolor 70 161 Enteromorpha clathrata 20 Epinephelus fasciatus 116 Erethmochelys imbricata 154 Erosaria nebrites 164 Erythrastrea 33 Euapta godeffroyi 97 Eucidaris metularia 94 Euphasia sp. 104 Euphendrium cf. ramosum 24 Eurypegasus draconis 112 Exalias brevis 134 95 Favia cf. rotundata 34 Favia cf. pallida 34 37 Favia favus 34 Favia laxa 34 Favia stelligera 34 42 Favia veroni 34 Favorinus tsurganus 80 Filogranella elatensis 75 Fromia monilis. 93 Fungia spp. 35 38 39 Fusinus polygonoides 79 Galaxea fascicularis 46 Gobiodon citrinus 137 Gomphosus coeruleus 124 181 Goniopora sp. 33 42 35 59 Gorgasia sillneri 109 Gracillaria 21 Grammistes sexlineatus 137 Gymnomuraena zebra 108 Gymnothorax flavimarginatus. 108 Gymnothorax nudivomer 127 Halocynthia 176 Halophila spp. 16 Hapalocarcinus marsupialis 89 Harpa amouretta 164 Hemigymnus fasciatus 124 Heniochus diphreutes 119 Heniochus intermedius 119, 163 Herpolitha limax 39 Heteractis aurora 70 Heteractis crispa 17 70 Heterocentrotus mammilatus. 94 Heteroxenia sp. 61 Hexabranchus sanguineus 81 Hippocampus histrix 110 Holacanthus xanthotis 121 Holothuria atra 96 Holothuria edulis 96 Holothuria hilla 96 Holothuria impatiens 97 Holothuria nobilis 96 Hydnophora exesa 50 Hydractinia 24 Hymenocera elegans 92 Hypselodoris infucata 80 Iago omanensis 104 Idiomysis tsurnamali 72 998

Inimicus filamentosus 115 Istiblennius edentulus 10 Istiblennius rivulatus. 134 Isurus sp. 18 104 Labroides dimidiatus 125 126 Laevichlamys superficialis 164 Lambis truncata sebae 77 Lamprometra klunzingeri 99 Leptoseris explanata. 52 Limaria fragilis 83 Lithophyllum 21 Litophyton arboreum 62 177 Lobophyllia cf. pachysepta 38 Lobophyllia corymbosa 45 179 Limaria fragilis 83 Lithophyllum 21 Litophyton arboreum 62 177 Lobophyllia cf. pachysepta 38 Lobophyllia corymbosa 45 179 Lotilia graciliosa 136 Lovenia elongata 94 Lysmata amboiensis 127 Macrophiothrix hirsuta 98 Manta birostris 18 106 Mauritia arabica immanis 77 Meiacanthus nigrolineatus 134 Meomeris annulata 21 Merulina cf. ampliata 52 Metopograpsus messor 11 Microcyphus rouseaui 94 Millepora dichotoma 25 134 Millepora platyphylla 25 29 Modiolus auriculatus 164 Monacanthus spp. 147 Montipora spp. 13 46 Mycale fistulifera 22 Mycedium umbra 49 Myrichthys maculosus 102 109 Myripristis murdjan 142 143 158 Naosithoe 22 Naso lituratus 139 Naso unicornis 139 Nassa situla 79 Negombata magnifica 22 62 Nemanthus annamensis 73 Neopomacentrus miryae 145 Nerita orbignyana 10 Nodilittorina subnodosa 11 Octopus cf. cyaneus 85 Octopus marginatus 86 Opheodesoma grisea 97 Ophiocoma scolopendrina 11 Ophiocoma valenciae 98 Opiothrix propinqua 98 Ostracion cubicus 148 Ostracion cyanurus 148 Ovabunda macrospiculata 61 Oxycirrhtes typus 67 131 Pachycerianthus 72 Pachyseris speciosa 49 Padina gymnospora 21 Palaemon debilis 10 Panulirus sp. 88 Papilloculiceps longiceps 133 Paracheilinus octotaenia 124 Paracirrhites forsteri 131 Paraglyphidodon melas 122

Paralemnalia 65 Parapercis hexophthalma 102 137 Parapriacanthus ransonneti 63 107 Pardachirus marmoratus 132 Parupeneus forsskali 130 Parupeneus cyclostomus 181 Pavona cactus 49 Pavona cf. varians 52 Pavona maldivensis 51 Pedum spondyloideum 82 Pempheris vanicolensis 144 Periclimenes imperator 127 Periclimenes longicarpus 127 Petroscirtes ancylodon 135 Petroscirtes mitratus 135 Phronima sp. 101 Phyllidia undulata 80 Pinna muricata 82 Plagiotremus rhinorhynchus 135 Platax orbicularis 141 Platygyra deadalea 43 47 Platygyra sp. 33 44 58 159 178 Plectropomus pessuliferus marisrubri 116 Pocillopora 41 Polinices mammila 79 Pomacanthus imperator 121 95 Pomacanthus maculosus 120 Pomacentrus sulfureus 122 Porites cf lutea 42 Porites cf. mayeri 47 Porites columnaris 14 48 Porites sp. 159 178 Priacanthus hamrur 142 Pseudanthias squamipinnis 113 117 143 145 176 Pseudanthias taeniatus 117 Pseudobalistes flavimarginatus 146 Pseudobalistes fuscus 91 146 Pseudobiceros Pseudoceros 75 Pseudochromis fridmani 137 Pseudorca crassidens 155 Pteria aegyptiaca 82 Pteroides sp. 69 Pterois miles 107 113 179 Pterois radiata 114 Ptychodera flava 16 101 Pygoplites diacanthus 121 Rhincodon typus 18 19 104 Rhinecanthus assasi 146 Rhytisma 161 Sabella sp. 75 Sabellastarte indica 74 Sabellastrate cf. sanctijosephi 75 Salpa maxima 101 Sarcophyton 60 Sargassum sp. 21 Sargocentron diadema 142 Scarus bicolor 129 Scarus ferrugineus 102 156 Scarus gibbus 128 129 Scarus niger 129 Scarus sordidus 129 Scleronephthya 64 Scolopsis ghanam 130 137

Scorpaenopsis diabolus 114 Scyllarides tridacnophagus 88 Sepia aculeata 84 Sepioteuthis sepioidea 84 Seriatopora hystrix 30 41 Serpulorbis inopertus 78 Siderea grisea 108 Siganus luridus 140 Siganus stellatus 140 Sinularia sp. 30 Siphonochalina siphonella 14 23 Siphonophora 24 Solenostemus cyanopterus 111 Solenostemus paradoxus 46 111 Sparus aurata 141 Sphyraena barracuda 18 Spirobranchus giganteus 31 74 Stenella attenuata 155 Stenopus hispidus 127 Stichopus spp. 96 Stoichactis gigas 123 Strombus spp. 164 Stylophora 41 123 Sufflamen albicaudatus 146 Symbiodinium (=zooxanthellae) 12 20 Synanceia verrucosa 115 Synapta reciprocans 97 Syngnathus 111 Synodus variegatus 107 133 153 Taeniura lymma 105 133 Tellinella virgata 164 Terebra maculata 164 Tetraclita squamosa 10 Tetrosomus gibbosus 148 Thais hippcastanum 10 Thalassoma klunzingeri 124 Thaumoctopus mimicus 85 87 Thor amboinensis 71 127 Torpedo sinuspersici 105 133 Torquigener flavimaculatus 151 Trachyphyllia geoffroyi 38 Trapezia tigrina 31 92 Triactis producta 71 Tridacna 44 83 88 157 172 Tridacna maxima 83 Tridacna squamosa 83 Tripneustes gratilla elatensis 94 158 Trochus dentatus 76 Tubastrea cocinea 55 Tubastrea micrantha 55 Tubipora musica 68 Tubularia larynx 24 Turbinaria elatensis 21 Turbinaria mesenterina 49 179 Turbo radiatus 76 Tursiops spp. 155 Tutufa rubeta 76 Tylosurus sp. 126 Variola louti 116 Xyrichtys pavo 153 Zebrasoma desjardinii 139 Zebrasoma xanthurus 139

187

Common Names

Acabaria 66 Acorn worm 16 101 Adhesive Anemone 71 Aeolidid slug 80 Ahermatypic corals 54 55 Anemone carrier crab 71 Anemone mysid 72 Angelfish 120 121 Arabian cowry 77 Arabian fangblenny 135 Arabian tongue sole 133 Banded boxer shrimp 127 Bannerfish 77 Barbed wire black-coral 56 57 Barnacles 10 25 Barracuda 18 Basket star 99 Basslets 113 117 145 175 Batfish 141 Bicolor puller 145 Bigeye 142 Bird wrasse 124 181 Bird’s nest coral 30 Black ascidian 175 Black corals 56 57 Blackbar surgeonfish 139 Blackline blenny 134 Blackringed cardinalfish 142 Blennies 10 134 135 Blue triggerfish 91 102 148 Boring sponge 22 Bottlenose dolphins 175 Boulder coral 14 42 -48 159 178 Boxfish (=Trunkfish) 148 Brain coral 43 - 47 58 159 178 Branched coral 40 41 45 65 Branched Table coral 43 Brittlestar 90 98 Broomtail wrasse 102 125 167 Brown algae 21 Bulldozer shrimp 136 Burrfish 149 Butterflyfish 118 119 Carrier hermit crab 16 179 Cauliflower Coral 41 Cave sweeper 144 Cephalopods 76 84 85 Chevron Butterflyfish 118 Chiton 10 76 Christmas tree worms 31 74 Circular spadefish 141 Citron goby 137 Clam-killer lobster 88 Clams 164 Cleaner shrimps 71 126 127 Cleaner wrasse 125 126 Clearfin lionfish 114 Clown wrasse 124 Clownfish 17 70 122 123 161 Clownfish Anemone 70 161 Colored broccoli coral 63 160 Columnar corals 48 Comb jellies 19 Commensal Anemone 70 Conch snails 164

188

Cones snails 76 Coral burying clam 82 Coral crabs 31 89 92 Coral gall crab 89 Coral grouper 116 Coral nurseries 165 Coral predating snail 159 Corallimorpharian Anemone 29 72 Corallivorous snail 159 Cowries 76 164 Crab Carried Anemone 71 Crocodile fish 133 Crown-of-thorn sea star 92 159 Cubefish 148 Cup coral 49 Cushion Anemone 123 Cushion seastar 93 Cuttlefish 84 Damsel fish 31 122 123 126 Devil scorpionfish 114 Domino dascyllus 122 Dorid slug 80 Double-spined urchin 94 95 Dragon fish 112 Eagle ray 105 Egyptian pearl oyster 82 Eightline wrasse 124 Eilat tubeworm 74 75 Electric ray 105 Elephant-ear coral 49 Emperor angelfish 121 Encrusting corals 46 65 Eyebar goby 137 False killer whale 155 Fan corals 67 131 Feather-stars 90 99 Filefish 147 Finger leather coral Fingered soft-coral 30 Fire coral 134 Fire sponge 22 Fire urchin 95 Fissured sand dollar 95 Fiveline cardinal 142 Flashlight fish 174 Flat fish 132 Flat worms 74 75 Flower pot coral 59 Foliaceous corals 49 Footballer damselfish 122 Fourlined cleaner wrasse 126 Freckled anglerfish 152 Frog snail 76 164 Frogfish 152 Galaxy coral 46 Garden eels 108 109 Geometric urchin 95 Ghostfish 46 111 Giant clams 83 172 Giant salp 101 Gilthead bream 141 Goatfish 130 153 Gobies 136 137 Goldies 113 117 145 175 Goldstriped cardinalfish 135 Gorgonian corals 13 66

Graceful goby 136 Green algae 20 21 Green broccoli coral 62 Green Chromis 31 122 123 145 153 Green sea turtle 154 Greenish synapta 97 Grey moray 108 Grey rope cucumber 97 Grey sponge 23 Groupers 116 Harlequin shrimp 92 Hawkbill sea turtle 154 Hawkfish 131 Heart urchin 95 Heavybeak parrotfish 128 129 Helmet shell 76 95 164 Hemisphere corals 42 Hermatypic corals 53 hermit crab 16 70 88 Hickson’s Fan coral 13 67 Highfin blenny 135 Hog wrasse 124 Honeycomb filefish 147 Horn coral 50 Hound shark 104 Hydroids 24 Indian tubeworm 74 Jellyfish polyp 22 Juvenile coral colonies 47 Klunzinger’s wrasse 102, 124 Krill 104 Laminar corals 52 Lance blenny 134 Land hermit crab 164 Large tube snails 78 Leaping blenny 135 Leather Anemone 17 70 Leather coral 60 Leatherjacket 147 Leopard flounder 132 Lettuce coral 49 51 Limpet 10 76 Lined Butterflyfish 118 119 Lionfish 113 114 179 Lizardfish 127 133 153 Lobed coral 45 179 Lobsters 88 Longspine urchin 16 94 125 Longnose Hawkfish 57 131 Longspine Porcupinefish 149 Lunartail grouper 116 Maculate Terebra 164 Mako shark 18, 104 Mangrove prawn 10 Manta ray 18, 106 Marble shrimp 88 Marbled snake eel 109 Marine worms 74 Masked butterflyfish 118 Masked puffer 150 Massive corals 42 Microatolls 58 Mimic blenny 134 Mimic octopus 87 Miry’s damsel 145 Moon Coral 42

Moon Jellyfish 26 Moon shell 79 Moray eels 108 Moses sole 132 Multibar pipefish 111 Mushroom corals 39 Mutable conch 164 Mysid 72 Spotted dolphin 155 Needlefish 126 Net Fire-coral 25 Nettle jellyfish 27 Noble sea cucumber 96 Nudibranchs 80 Octocorals 28 60 - 66 Octopuses 76 84-86 Open Sea life 19 Opercleless tubesnail 78 Opisthobranch snails 80 Orange sponge 23 Orangespine unicornfish 139 Orchid dottyback 137 Organ pipe Coral 68 Organ pipe sponge 14 Ornate pipefish 111 Pajama slug 22 178 Pallid broccoli coral 64 Paper nautilus 85 Parrotfish 102 128 129 174 Partner shrimps 127 Pearl oyster 82 Pearl sea star 93 Pearl toby 151 Pearlfish 96 Periwinkle 11 Pigmy sea star 92 93 Pigmy sweeper 107 144 Pipefish 110 111 Pixy hawkfish 131 Plate coral 47 49 179 Plate Fire-coral 25 29 Plate-like corals 52 Polished Nerita 10 Porcupinefish 149 Pram bug Amphipod 101 Prawns 88 Prostrate soft corals 161 Pufferfish 150 Pulsating soft corals 61 Rabbitfish 140 Rays 105 Razorfish 153 Red algae 21 Red and violet broccoli coral 63 Red keyhole sponge 22 Red Sea bannerfish 163 Red Sea bottlenose dolphin 155 Red Sea goatfish 130 Red Sea minipuffer 151 Red Sea picasso fish 148 Red Sea roving grouper 116 Redmouth grouper 107 116 Reef brittle star 98 Reef feather star 99 Rockskipper 134 Rope cucumber 97

Royal angelfish 121 Royal damselfish 122 Rusty parrotfish 156 Sabretoothed blenny 134 135 Sailfin tang 139 Salps (tunicates) 101 Sand dollar 91 95 Sand penshell 82 Sandal coral 39 Scribbled leatherjacket 147 Scyphozoa 26 Sea Anemones 70-73 127 161 Sea breams 141 Sea cucumber 90 96 97 127 Sea harp 164 Sea horse 110 111 Sea Pen 69 sea slugs 76 80 Sea squirts 89 100 Sea stars 17 90-92 Sea turtles 154 Sea urchins 90 94 95 Seagrass 16 Seagrass ghostfish 111 Sergeant majors 122 Sharp mushroom coral 39 Shell octopus 86 Shield slug 80 Shore brittle star 11 Shorecrab 11 Shortbodied blenny 134 Shortfin lionfish 114 Shortspine velvet urchin 94 158 Shrimp gobies 136 Shrimpfish 110 Siphonophora 24 Skates and rays 105 106 Slate pencil urchin 95 Snake eel 102 108 109 Snowflake moray 108 Soapfish 137 Social ascidian 100 Soft corals 28 29 54 60-66 Sohal surgeonfish 138 Solitary corals 38 Spanish dancer 81 Speckled brittle star 98 Speckled sandperch 102 137 Spider conch 77 Spindle snails 79 Spinecheek 130 137 Spiny Murex 164 Sponge carrier 89 Spotfin anglerfish 152 Spottail wrasse 124 126 Spotted snake eel 109 Squaretail rabbitfish 140 Squat cleaner shrimp 71 127 Squid 76 84 Squirrelfish 142 Staghorn coral 40 46 47 Stellate puffer 150 Stellate rabbitfish 140 Sticky sea cucumber 97 Sting ray 105 Stingfish 115 Stonefish 114 115

Stony corals 13 29-52 Striped Butterflyfish 118 145 Striped Engina 77 Striped goldfish 117 Striped tubeworm 75 Subtidal brittle star 98 Suckerfish 106 Sulphur damselfish 122 Sunray Anemone 70 Surgeonfish 138 139 Sweepers 144 Swimming clam 83 Tenlined urchin 95 Thicklip wrasse 124 Thornback trunkfish 148 Thorny seahorse 110 Threadfin butterflyfish 118 119 159 Tiger Anemone 73 Tiger cardinalfish 135 Tigertail sea cucumber 96 Tobies 151 Top shell 76 Tree Black-coral 56 Tree-coral 65 Triggerfish 148 Triton trumpet 92 Trunkfish 148 Trush cowrie 164 Tube Anemone 72 Tube sponge 23 98 Tube worm 75 Tubercle coral 46 Tubercle sea cucumber 96 Tunicate 175 Turban snail 76 Twobar bream 141 Unicornfish 139 Upside-down Jellyfish 26 Variable “hybrids” 50 51 Variable coral crab 89 Waving hand coral 64 Whale shark 18 19 104 Whales 155 Whelk 10 79 White Banded cleaner shrimp 127 White spotted octopus 85 White-edged soldierfish 142 158 Worms 74 75 Wrapper Sea-Anemones 73 Wrasses 91 124-126 Yellow spotted burrfish 149 Yellowbar angelfish 120 Yellowear angelfish 121 Yellowface soapfish 137 Yellowmargin moray 108 Yellowmargin triggerfish 148 Yellowmouthed moray 127 Yellowtail tang 139 Yellowtail wrasse 124 Zebra moray 108

189

Photo Credits

The book contains 560 photographs, generously donated by the following photographers, most of them members of the “Tapuz” divers’ forum* photographers* Aharoni Ygal Armosa Omer Ben-Tov Ilan Biran Ronen Chen Mori Cohen Razi Colorni Angelo Dafni Lior Diamant Ariel Esh Yahav Grinfeld Javier Gur Amir Halevi Elad Kendler Assaf Koslevski Robert Lederman Oren Levi Bader Levi Keren Lynn Anat Meidn Eldan Movshowitz Ziv Pinchover Liron Poupin J. Schuhmacher H. Shafir Shai Shpigel muki Shshar Nadav Stern Amir Tamir Ben Weinberg Danny

Pages 81 , 110 , 111 , 125 , 144, 147 , 152 155 19 , 31 , 36 , 55 , 57 , 67 , 73 , 86 , 88 , 89 , 99 , 107 126 , 179 88 7 38 26 , 39 , 55 , 59 , 75 , 149 14 , 31 , 54 , 71 , 117, 171 90 , 92 , 121 101 104 81 , 85 108 , 127 , 139 104 117 , 124 27 , 57 , 71 , 83 , 92 89 , 140 , 193 97 , 115 118 118 109 , 124 176 89 12 40 , 165 , 166 101 85 127 , 136 18 , 72 , 93, 97 , 111 , 113 , 137 , 139, 149 33 , 37 , 86 , 89 , 126 , 135 , 147

*All other pictures were taken by Jacob Dafni and Michael Levin ** Throughout the book, the credits are arranged according to the order of the pictures from the upper left, and in a clockwise direction.

190