Lecture 1&2_ Intro , Protozoa , Por If Era

ANIMAL BIODIVERSITY

BIODIVERSITY Biological Diversity Can be observed at 3 levels: Genetic diversity – Species diversity – Ecosystem diversity –

SPECIES DIVERSITY Diversity of organisms on earth

ECOSYSTEM DIVERSITY • Diversity in habitat, biota community, ecological processes in the terrestrial, marine and other aquatic systems

IMPORTANCE OF BIODIVERSITY • • • • •

Economic importance Food Environmental stability Our heritage Scientific, educational and recreational value • Biological safety

ANIMAL CHARACTERISTICS ∀• ∀• ∀• ∀• ∀• ∀• ∀• ∀• ∀• ∀•

Eukariot Multicellular No cell wall Can be differentiated through feeding methods Digest their food Respire React to stimulus Able to move Excrete Transport food in the body

Eucaryotic Cell

ANIMALS: How many species exist? • A few years back: – estimate 2 – 8 million – 1.4 million known to science

• Now: – Estimate 30 – 50 million species

TRADITIONALLY CAN BE GROUPED BASED ON ON CHARACTERISTICS ASSOCIATED WITH THEIR EMBRYONIC DEVELOPMENT

• Number of layers of primary tissue diploblastic, triploblastic • Is there a coelom formed and how was it formed; • Cell alignment during cleavage; • What is formed from the blastopore; and • Body symmetry

Animal Development Example : sea urchin • Development of the blastula is the earliest development stage of the embryo • Firstly the unicellular zygote divides into two in a process called cleavage

8-cell stage

Animal Development (cont.) • Both cells continue to divide until a 1-cell layer hollow ball called blastula is formed • The space in the blastula is filled with fluid • For sea urchin, formation of the blastula completes 10 hours after fertilization.

Animal Development (cont.) • External layer of blastula folds inward until a 2-layer structure called gastrula is formed • External cell layer is called ectoderm and the inside called endoderm. • The mesoderm is formed in between

Animal Development (cont.) • Ectoderm develops to form skin and nerve tissues; • Endoderm forms the digestive system; • Mesoderm forms the muscle, reproductive organs and circulatory system • For deuterosomes, the mesoderm is formed from a clump of cells detached from the endoderm

Animal Body Cavity Acoelomate – no cavity Pseudocoelomate – not true cavity ie. false cavity Coelomate – true body cavity

Blue – ectoderm, Red – mesoderm, Yellow - endoderm

Animal Body Cavity - Acoelom • • • •

Example – flat worm; Body made up of 3 layers(tripoblastik); Possess digestive tract but no body cavity; First animal class where muscle and other organs evolved from the mesoderm; • Organs buried in mesodermal tissue; and • Water and digested food move along body through absorption.

Internal parts of a Planaria (flat worm)

Animal Body Cavity - Pseudocoelom • • • • • • • •

Example – nematode; Size: 400µm to 5 mm; One of the most abundant animal on earth; Fluid-filled pseudocoelom forms between endoderm and mesoderm Cavity not lined with mesothelium (as in eucoelom) Enable animals to move more effectively, esp. in terms of muscle function; Organs buried in mesodermal tissue; and Another eg.: Phylum Rotifera

A nematode

Coelom • Body cavity covers the entire vertebral column; • Cavity lined with mesothelium • Divides body into inner and outer tubes; • During development, coelom divides into various components.

EXAMPLES OF COELOM COMPONENTS • Fish – Pericardium (around the heart) – Pleuroperitonium (around other viscera)

• Mammals – Pericardium (around the heart) – Pleuron (around the lungs) – Peritonium (around other viscera)

ANIMAL BODY FORMS AND THEIR ADAPTATION What is meant by body symmetry? Symmetry refers to the balance of an animal body

Kinds of symmetry:

Asymmetry • Eg. sponge (Filum Porifera) • Normally sessile animals • No distinct symmetry

Kinds of symmetry (cont.)

Radial Symmetry • Eg. Hydra (Phylum Coelentrata); • Can be divided in any plane; • Radial symmetry is an adaptation by Hydra to enable it to detect and catch prey from any angle.

Cross section of a Hydra

Kinds of symmetry:

Bilateral Symmetry

• Left and right sections mirror image of the other; • Anterior section different from posterior • Dorsal area different from ventral • All animals with bilateral symmetry possess a body cavity where all the organs are located; • Due to the presence of body cavity, animals can grow to a bigger size and are able to move and feed effectively; • Without body cavity animals will have to depend on absorption for food.

Flat Worm- external features

A B 1 2 3 4 5 6 7 8 9 10 11

dorsal dorsal and ventral head anterior posterior eye spot Sensory lobe dorsal Mouth Pharynx (extended during feeding) Pharynx opening Genitalopeningl Ciliated ventral surface.

Internal sections of a Planaria

Example of a planaria Dugesia sp

THE ANIMAL KINGDOM

Porifera

Others

Parazoa

Metazoa

Colonial Protist Early division of animal kingdom

Mollusca Annelida Arthropoda

Animal Groups

Echinodermata Chordata

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ANIMAL KINGDOM Subkingdom Invertebrata – – – –

Larger in numbers Many without skeleton Some only with exoskeleton A few with endoskeleton

Subkingdom Vertebrata – Possess a notochord – During adult stage notochord replaced with vertebra – Brain contained in a cranium

ANIMAL KINGDOM Invertebrata – – – – – – – – –

Protozoa Porifera Coelentrata Annelida Mollusca Platyhelminthes Nematoda Arthropoda Echinodermata

Vertebrata – – – – –

Fish Amphibia Reptilia Aves Mammalia

PHYLUM PROTOZOA • • • • •

Smallest animals Now placed in Kingdom Protista Body made up of one cell Free-living or parasitic Parasitic protozoa cause illness such as malaria, dysentery and others; • Found in freshwater or marine environment • Some marine species excrete skin made of calcium

Free-living Protozoa: Some forms of Foraminifera – Marine protozoa with external shell

Paramaecium – freshwater

Protozoa - Euglena

Euglena can change form easily Hundreds of Euglena in a single drop of water

PARASITIC PROTOZOA Species Trypanosoma brucei gambiensis Plasmodium malariae Entamoeba

Illness chronic sleeping sickness Malaria Amoebic dysentery

PHYLUM PORIFERA

Basic Morfology of Sponge

PHYLUM PORIFERA – SOME CHARACTERISTICS • Represents all sp of sponges (about 5000 sp) • Only representative of Parazoa (animals without true tissue) • Almost all –radial symmetry • Almost all made up of 3-layered cell • Outer layer made up of flattened cells with numerous pores;

PORIFERA CHARACTERISTICS (cont) • Middle layer contains mobile cells (amoebocytes or archaeocytes) and skeletel cells – skeletal cells in form of spogin (flexible protein) or mineral containing particles; – amoebacytes: collect food vacoules from coanocytes, digest food and send to cells that require it. • Inner layer made completely of cells called choanocytes •Do not have digestive tract, nerve cells or muscle cells.

CLASSIFICATION OF PORIFERA

At one time, a diagnostic feature of the Porifera was the presence of spicules

As a result, certain fossil groups whose organization was consistent with that of living sponges were not placed within the phylum Porifera. These are groups with a solid calcareous skeleton

4 Different Forms of Spicules Megascleres – large, can be seen with naked eyes

Microscleres - small

SEM of Spicules

CLASSES IN PHYLUM PORIFERA • Calcarea • Demospongia • Hexactinellida

CLASSIFICATION OF SPONGES

Archaeocyatha – no living representative

Stromatoporoids

Choanoflagellates

• •

• • •

Class Calcispongiae (Calcarea) Spicules formed from calcium carbonate; Spicules in the form of needles or with 3 or 4 branches; Spicules not hollow (stronger); All marine members; Leucosolenia sp Most in shallow waters.

CLASS DEMOSPONGIAE • Abour 90% sponges in this class; • Spicules formed from spongin, silica or both; • Can grow to large size; • Found in all tropical and sub-tropical waters; and • One FW family Bath sponge

CLASS HEXACTINELLIDA • Spicules formed from silica (sometimes called glass sponge); • Spicules joined at 90o angle – make it seem like artificial sponge; • Spicules with 6 branches; • Almost all extinct

Aphrocallistes sp

Three groupings of sponges based on water circulation system • Asconoid (eg Leucosolenia sp) • Syconoid (eg. Scypha) • Leuconoid

Groupings based on water circulation system

TYPICAL SPONGE FEEDING -

Water flowing through sponges provides food and oxygen, as well as a means for waste removal -Can filter up to 20,000 times its volume in a single 24 hour period - Feed on bacteria – can trap up to 90% of bacteria in water - Some sponges harbour symbionts such as green algae, dinoflagellates, or cyanobacteria, from which they also derive nutrients.

CARNIVOROUS SPONGE • Family Cladorhizidae • Feed by capturing and digesting whole animals. • Use spicules to capture • Prey – small crustaceans