Ecology And Animal Behavior

ECOLOGY AND ANIMAL BEHAVIOR Importance of the study: 1. To create public awareness of dangers to the environment caused by human population increase and technological expansion 2. The science can be a tool to understand and cope with emerging problems, such as water and air pollution and the indiscriminate use of herbicides and pesticides 3. To understand how plant, animal, and aquatic life cope with the ever changing environment ECOLOGY * etymology: eco = house / home ; logy = study of > study of homes and/or house * coined by Ernst Haeckel, a German zoologist in 1866 * older authors described the subject as the “natural history” or “bionomics” > study of the living animals and plants in their natural environment * study of the relations between organisms and their environment > more specifically, the study of the interaction and interrelation of organisms in their respective communities ( plant and animal ) 2. Chemical Environment a. Terrestrial - chemical composition of the soil and water supply - basic to plants - far reaching but with indirect effects on the animal communities - high importance to aquatic organisms 3. Biological Environment * biological factors of the environment consists of the interrelations of organisms in communities * many organisms are complexly associated with nature Biological…. * there is a reciprocal relationship between the biological community and the inorganic environment ex. type of forest depend on soil type > soil type is the product of forest temperature, humidity, and light conditions within are the results of vegetation >> forest climate determines the type of community that will inhabit the forest 4. Limiting Factors - in the form of: environmental temperatures, water salinity, availability of food Biotic Factors - etymology: bios = life - includes: organisms within the environment food supply Abiotic Factors - etymology: a = without ; bios = life - includes physical conditions such as: temperature Weather, altitude, availability, water and light

Relationships Occurring in the Biosphere: 1. Interaction among biotic factors A. Competition for food resources * animals depending on plant life for food are found where plants are growing. ex. deer, gazelle, impala * animals eating plant-eating animals are found near the plants. ex. lions, tigers * lions and tigers competing with other animals like hyenas and vulture when feeding Predation - type of interaction in which one animal hunts or seizes another animal eats it for its food Predator - animal that’s hunt, seize, and eat other animals for food Prey - animal that is hunted, seized, and eaten by the predator Food Chain - the transfer of energy from the deer then to the tigers - chief source of energy of the food chain: SUN B. Competition among male and female animals for a mate C. Close association relationship among organisms ex. lichen = alga and fungus > form of controlled parasitism >> alga eventually dies D. Interaction among organisms - to increase their chances of survival - perpetuate and preserve the species ex. hookworm (parasite) looking for an animal (host) to survive 2. Interaction among Physical factors A. Temporary changes ex. clouds covering the earth > reduce amount of sunlight to earth B. Permanent changes ex. floods, earthquake, volcano eruption > may alter the shape of a river or lake > may change sedimentation rate > may alter the landscape 3. Interaction between Biotic and Abiotic (Physical) factors * life depends on Resources Limiting factor - when the demand for a particular resource is greater than its availability > may limit the number of organisms that can live in a particular place ex. a. lack of water - plants die ; animals either leave or die b. oxygen - fishes need oxygen > physical factors like tides, currents, location of continents, wind strength, water temperature can create areas of low oxygen >> fishes leave the area or die

Carbon - Oxygen Cycle * involved in two basic life processes: a. Respiration ( plant and animal) b. Photosynthesis (only green plants) * cellular respiration > glucose is oxidized >> CO2 is released * photosynthesis > green plants use H2O, CO2, and sun’s energy >> creates O2, glucose and water Sources of CO2: a. Organism’s death - eventual microbial breakdown of its organic compounds b. Fossil fuel burning - carbon compounds of ancient plants and animals are stored in the form of coal and petroleum > burning >> CO2 is released into the air and atmosphere Carbon cycle: CO2 in the air > glucose >> CO2 Nitrogen Cycle: * atmosphere is 78% Nitrogen by volume * often a limiting factor in plant growth > plants cannot change Nitrogen to elements need for its manufacture of structural proteins and enzymes >> has to be in NITRATE form for the plants to absorb and use Natural sources of nitrates: A. Nitrogen fixing ( Fixation ) ex. Azolla, Rhizobium , blue green algae B. Atmospheric reaction during thunderstorms ex. lightning causes nitrate ion formation from atmospheric nitrogen C. Erosion of Nitrate - rich rocks > materials flow downstream to rivers and banks D. Nitrification > protein from dead organisms E. Denitrification (soil to atmosphere ) ex. plowing > anaerobic bacteria (abundant in tightly packed waterlogged soil) causes release of free nitrogen from the soil * well drained cultivated fields = no problem with denitrification F. Carnivorous plants using animal proteins as a nitrogen source ex. Venus flytrap, Butterwort, Sundew Water Cycle * essential to life ex. chemical reactions in body * cells made up of water mainly ; recyclable * transport medium of minerals to other parts of organisms * many organisms live in a water environment * plants - absorb water from roots > transpiration process >> water vapor emission from its leaves * animals - drink water > give off when exhaling

* lakes, rivers, streams, oceans, and plants act as water reservoirs Evaporation - the sun’s energy causes water to move into the atmosphere Precipitation - water moving down from the atmosphere to earth BIOMES * areas of the biosphere that can be identified by a dominant animal and plant species; with no sharp boundaries > gradual merging Biomes * defined as "the world's major communities, classified according to the predominant vegetation and characterized by adaptations of organisms to that particular environment" (Campbell 1996) * the importance of biomes cannot be overestimated. > Biomes have changed and moved many times during the history of life on Earth. * more recently, human activities have drastically altered these communities > thus, conservation and preservation of biomes should be a major concern to all * increasing human activity has rapidly destroyed or polluted many ecological habitats throughout the world. > it is important to preserve all types of biomes as each houses many unique forms of life However, the continued heavy exploitation of certain biomes, such as the forest, freshwater, and marine, may have more severe implications Types of Biome: 1. Terrestrial - most varied 2. Freshwater 3. Marine - contains more dissolved salts than the freshwater biomes Terrestrial Biome * contains the climax vegetation ( group of plants dominating a terrestrial biome) * climate (amount of rainfall, land configuration, temperature, sunlight etc) > determines/ influences the type of vegetation or animals living in the area * specific terrestrial biomes: Tundra Coniferous Forests Deciduous Forests Rain Forests Grasslands Deserts Tundra * the coldest of all the biomes ; dry climate

* Tundra comes from the Finnish word tunturi, meaning treeless plain * large area encircling the Arctic Ocean * Southern Hemisphere (Alpine tundra) landmass is small as compared to the Northern Hemisphere (Arctic tundra) Permafrost – ground is permanently frozen about a meter from the surface * continuous summer light > surface thaws >> bogs, streams, ponds are formed Characteristics of a Tundra 1. Extremely cold climate > fierce winds blow while snow and ice cover the ground. Even the sea freezes as the temperature gets colder > average yearly temperature is only 10 to 20 degrees F > sometimes the strong winds create "white outs" when the snow blows so much that it is hard to see! White outs last for days. > noted for its frost-molded landscapes 2. Low biotic diversity > animals - with white coats for protection and stealth ex. Polar bears, caribou, arctic hares, arctic foxes, and insects laying freeze resistant eggs > mammals and birds also have additional insulation from fat > The fauna in the arctic is also diverse: Herbivorous mammals: lemmings, voles, caribou, arctic hares and squirrels Carnivorous mammals: arctic foxes, wolves, and polar bears Migratory birds: ravens, snow buntings, falcons, loons, ravens, sandpipers, terns, snow birds, and various species of gulls Insects: mosquitoes, flies, moths, grasshoppers, blackflies and arctic bumble bees Fish: cod, flatfish, salmon, and trout 3. Simple vegetation structure > main vegetation: moss, lichen, grasses, small woody plants > All of the plants are adapted to sweeping winds and disturbances of the soil > plants are short and group together to resist the cold temperatures and are protected by the snow during the winter > the only tree that grows in the tundra is the dwarf willow tree. It grows to a maximum of four inches tall. > they can carry out photosynthesis at low temperatures and low light intensities 4. Limitation of drainage > The tundra receives less than 10 inches of precipitation yearly 5. Short season of growth and reproduction > short summer that lasts from May to July. > during summer, the temperature only rises to about 50 degrees F > most plants reproduce by budding and division rather than sexually by flowering

* In the summer months, the sun shines all the time, even at midnight. 6. Energy and nutrients in the form of dead organic material > The two major nutrients are nitrogen and phosphorus Nitrogen is created by biological fixation Phosphorus is created by precipitation 7. Large population oscillations > Animals are adapted to handle long, cold winters and to breed and raise young quickly in the summer. > many animals hibernate during the winter because food is not abundant. > another alternative is to migrate south in the winter, like birds do. > reptiles and amphibians are few or absent because of the extremely cold temperatures. * Every ten or thirteen years, the small mammals in the tundra breed in large numbers > the larger animals also grow in number because of the increase in their food supply >> soon the small mammals run out of plants to eat and many die >>> the larger animals begin to die and then the plants can grow back * Because of constant immigration and emigration, the population continually oscillates. Animal adaptation * a large variety of animals live in the tundra for the whole year. * they have special adaptations that allow them to survive in the winter weather. > some of these include: short legs; long hair; and a coat of thick fur short tails and large, furry feet. many animals have white fur which camoflauges them against the snow FOREST BIOME * about 420 million years ago, during the Silurian Period, ancient plants and arthropods began to occupy the land * over the millions of years that followed, these land colonizers developed and adapted to their new habitat * the first forests were dominated by giant horsetails, club mosses, and ferns that stood up to 40 feet tall * life on Earth continued to evolve, and in the late Paleozoic, gymnosperms appeared * Triassic Period (245-208 mya), gymnosperms dominated the Earth's forests * Cretaceous Period (144-65m mya), the first flowering plants (angiosperms) appeared > evolved together with insects, birds, and mammals and radiated rapidly, dominating the landscape by the end of the Period * The landscape changed again during the Pleistocene Ice Ages > the surface of the planet that had been dominated by tropical forests for millions of years changed >> temperate forests spread in the Northern Hemisphere

*** forests are becoming major casualties of civilization as human populations have increased over the past several thousand years > bringing deforestation, pollution, and industrial usage problems to this important biome * present-day forest biomes, biological communities that are dominated by trees and other woody vegetation (Spurr and Barnes 1980) can be classified according to numerous characteristics > with seasonality being the most widely used * there are three major types of forests, classed according to latitude: 1. Tropical 2. Temperate 3. Boreal forests (Taiga) BOREAL FOREST (TAIGA) * represent the largest terrestrial biome in the world * forest is covered with coniferous trees > sometimes the taiga is called a coniferous forest * occurring between 50 and 60 degrees north latitudes, boreal forests can be found in the broad belt of Eurasia and North America: 2/3 in Siberia with the rest in Scandinavia, Alaska, and Canada * seasons are divided into short, moist, and moderately warm and rainy and long, cold, and dry winters * the length of the growing season in a boreal forests is 130 days * temperatures are very low - 65 degrees BELOW zero * precipitation is primarily in the form of snow, 40-100 cm annually * 12-33 inches of rain in one year * soil is thin, nutrient-poor, and acidic CONIFEROUS FOREST (aka Boreal Forest / Taiga) * South of the Tundra in Europe, Asia, and North America * consists of evergreens or cone-bearing trees e.g. pines, firs, spruces, cedars * animals: moose, black bear, martens, wolverines, lynxes, beavers, porcupines, bobcat, fox, birds and insects (summer) and wolf > eats chipmunks, squirrels, rabbits, and mice * animals adapted to long cold winters Characteristics of Boreal Forest (Taiga) * seasons are divided into short, moist, and moderately warm summers and long, cold, and dry winters * the length of the growing season in boreal forests is 130 days * temperatures are very low * precipitation is primarily in the form of snow, 40-100 cm annually * soil is thin, nutrient-poor, and acidic * canopy permits low light penetration, and as a result, understory is limited Flora: consist mostly of cold-tolerant evergreen conifers with needle-like leaves, such as pine, fir, and spruce * conifer trees are often called evergreens - trees having long, waxy needles instead of wide, flat leaves like hardwood trees

> evergreens do not loose their needles come wintertime >> needles stay on all year long Fauna: woodpeckers, hawks, moose, bear, weasel, lynx, fox, wolf, deer, hares, chipmunks, shrews, and bats Note: current extensive logging in boreal forests may soon cause their disappearance BOREAL FOREST (TAIGA) * Canopy permits low light penetration, and as a result, understory is limited * animals who live in the taiga must be ready for some cold weather in the winter and some really warm weather in the summertime * during the summer, the taiga fills up with hundreds of insects. Birds come from all over the world hungry and ready to eat all the insects. Animals in a Taiga Moose - a large animal with huge antlers. It lives in areas near lakes and streams Bald Eagle - has a head covered in white feathers which makes it look bald - an endangered species - this huge bird likes to eat fish - has powerful wings and great eye sight to help it find it's food Weasel - a small animal that runs along the forest floor. It is small enough to get into the tunnels that mice and voles have created and then catches them to eat Fox - has a red coat and a bushy tail. It is a very good hunter. It eats anything from rodents, rabbits to fruits and sometimes garbage. RAIN FOREST (TROPICAL RAIN FOREST) * found on or near the equator all around the earth * abundant water supply and a long growing season * high rate of productivity: abundant resources favorable physical factors ex. warm temperature speeds up growth Jungle - area of very dense ground growth along the riverbanks, or in land once cleared by man or by some natural event like flood or fire - immature rain forest * equator is an imaginary belt which circles the earth and divides it into two halves > near the equator, the sun shines directly on the earth Tropics - areas directly above and below the equator - always warm and humid, much like summertime * most tropical rain forests are located on the continents of Central and South America, Africa, Asia and Australia. * the largest tropical rain forest in the world is the Amazon Rain Forest in South America - The world's largest river, the Amazon, flows through it > much of this rain forest is in the country of Brazil

* many different types of rain forests - can grow on mountains, seacoasts, plains, or in river valleys Characteristics of a Tropical forest * the greatest diversity of species - billions of species * occur near the equator, within the area bounded by latitudes 23.5 degrees N and 23.5 degrees S * the major characteristics of tropical forests is their distinct seasonality - winter is absent - only two seasons are present (rainy and dry) > the wettest place on earth. It rains every day. >> In one year it may rain about 100 to 400 inches or 9 to 30 feet of rain may fall each year. - length of daylight is 12 hours with little variations - seasons do not change in the tropical rain forest. It has been hot and wet for millions of years * temperature is on average 20-25° C / 80 F > the average temperatures of the three warmest and three coldest months do not differ by more than 5 degrees * precipitation is evenly distributed throughout the year, with annual rainfall exceeding 2000 mm * soil is nutrient-poor and acidic > decomposition is rapid and soils are subject to heavy leaching * canopy in tropical forests is multilayered and continuous, allowing little light penetration The Layers of the Rainforest The rain forest is divided into four main layers. Different kinds of trees, flowers, and other plants grow in each layer. 1. Emergent Layer - the Top Layer - these huge trees rise above all other trees in the forest and grow to 150 ft. tall - receive the most sunlight 2. Canopy (Cover) - the Next Layer - the treetops, or crowns, grow very close together and form a lush green garden in the air - rich with plants, animals and insects > many beautiful birds, butterflies, hummingbirds, and flowering plants live here > monkeys, bats, reptiles, and other animals swing, swoop, and climb through the canopy 3. Understory - the Middle Layer - smaller trees, bushes, and plants such as ferns, live in the understory - not much sunlight reaches here, because the canopy blocks the sun - many birds and animals make their home in the understory > forest wildcats, such as the leopard, are excellent tree climbers >>l chase monkeys and squirrels through the understory for food 4. Forest Floor - The Bottom Layer - few plants grow on the forest floor because almost

no sunlight reaches here - leaves and plants which drop from the upper layers provide food and shelter for animals and insects who live on the forest floor - mice, frogs, snakes and insects look for food here - larger animals, such as wild boar and deer, also make the forest floor their home Further subdivisions of this group are determined by seasonal distribution of rainfall: 1. Evergreen rainforest - no dry season 2. Seasonal rainforest - short dry period in a very wet tropical region > exhibits definite seasonal changes as trees undergo developmental changes simultaneously, but the general character of vegetation remains the same as in evergreen rainforests 3. Semi-evergreen forest - longer dry season > the upper tree story consists of deciduous trees, while the lower story is still evergreen 4. Moist/dry deciduous forest (monsoon) - length of the dry season increases further as rainfall decreases >> all trees are deciduous Note: More than one half of tropical forests have already been destroyed * Flora is highly diverse: - one square kilometer may contain as many as 100 different tree species. - trees are 25-35 meter tall, with buttressed trunks and shallow roots, mostly evergreen, with large dark green leaves examples of plants: orchids, bromeliads, vines (lianas), ferns, mosses, and palms * Fauna includes: numerous birds, bats, small mammals, and insects > animals and insects live in all the layers of the rainforest > some prefer the emergent layer, some the canopy, understory, or the forest floor * the heat and moisture in the rainforest cause plants and animals to rot quickly once they have died (called decay) > when things decay, all the rich nutrients are recycled back into the soil to feed the roots of other plants * Rain forests even recycle their rain! > as water evaporates from the forest back into the air, it forms clouds above the canopy >> the clouds will rain once again over the forest Scientists think destroying rainforests makes our earth warmer. This is called the Greenhouse Effect > without rainforests, we will have less rain.

>> harm the trees and plants that help to keep the air we breathe clean >>> our earth could become very dry and barren, like a desert MAMMALS Bats Chimpanzee Jaguar Lemur Leopard Mice Opossum Sloth Squirrel REPTILES Lizard Snake Turtle AMPHIBIANS Frog Salamander BIRDS Bird of Paradise Cockatoo Eagle Hummingbird Macaw Parrot Peacock Toucan INSECTS Ant Beetle Butterfly Snail Spider Termite Temperate Forest / Deciduous Forest * occur in eastern North America, Northeastern Asia, and Western and Central Europe * Distinctions/ Characteristics: > well -defined seasons with a distinct winter > moderate climate > a growing season of 140-200 days during 4-6 frostfree months > temperature varies from -30° C to 30° C. > precipitation (75-150 cm) is distributed evenly throughout the year > soil is fertile, enriched with decaying litter > canopy is moderately dense and allows light to penetrate >> resulting in well-developed and richly diversified understory vegetation and stratification of animals

* Flora: characterized by 3-4 tree species per square kilometer > trees are distinguished by broad leaves that are lost annually ex. oak, hickory, beech, hemlock, maple, basswood, cottonwood, elm, willow, and spring-flowering herbs * Fauna: represented by squirrels, rabbits, skunks, birds, deer, mountain lion, bobcat, timber wolf, fox, and black bear * soil can range from sandy and fine-textured to loose rock fragments, gravel or sand * has a fairly low salt concentration, compared to deserts which receive a lot of rain (acquiring higher salt concentrations as a result) * in areas such as mountain slopes, the soil is shallow, rocky or gravely with good drainage * in the upper bajada (lower slopes), they are coarse-textured, rocky, well- drained and partly "laid by rock bench" * in the lower bajada (bottom land), the soil is sandy and finetextured, often with "caliche hardpan" >> in each case, there is no subsurface water * the spiny nature of many plants in semiarid deserts provides protection in a hazardous environment - large numbers of spines shade the surface enough to significantly reduce transpiration - the same may be true of the hairs on the woolly desert plants * many plants have silvery or glossy leaves, allowing them to reflect more radiant energy > often have an unfavorable odor or taste * Semiarid plants include: Creosote bush, bur sage (Franseria dumosa or F. deltoidea), white thorn, cat claw, mesquite, brittle bushes (Encelia farinosa), lyciums, and jujube * during the day, insects move around twigs to stay on the shady side * jack rabbits follow the moving shadow of a cactus or shrub * naturally, many animals find protection in underground burrows where they are insulated from both heat and aridity ex. animals: mammals such as the kangaroo rats, rabbits, and skunks insects : grasshoppers and ants reptiles: lizards and snakes birds: burrowing owls and the California thrasher Coastal desert * occur in moderately cool to warm areas such as the Neararctic and Neotropical realm ex. Atacama of Chile * cool winters of coastal deserts are followed by moderately long, warm summers > average summer temperature ranges from 13-24° C * winter temperatures are 5° C or below * maximum annual temperature is about 35° C and the minimum is about -4° C > in Chile, the temperature ranges from -2 to 5° C in July and 21-25° C in January * average rainfall measures 8-13 cm in many areas * maximum annual precipitation over a long period of years has been 37 cm with a minimum of 5 cm

Cold desert Lichen growing on Torgerson Island, Antarctica; kangaroo rat * characterized by cold winters with snowfall and high overall rainfall throughout the winter and occasionally over the summer * occur in the Antarctic, Greenland and the Nearctic realm * have short, moist, and moderately warm summers with fairly long, cold winters * mean winter temperature is between -2 to 4° C and the mean summer temperature is between 21-26° C * winters receive quite a bit of snow * mean annual precipitation ranges from 15-26 cm - annual precipitation has reached a maximum of 46 cm and a minimum of 9 cm * heaviest rainfall of the spring is usually in April or May > in some areas, rainfall can be heavy in autumn * soil is heavy, silty, and salty > contains alluvial fans where soil is relatively porous and drainage is good so that most of the salt has been leached out * plants are widely scattered - areas of shadscale, about 10 percent of the ground is covered, but in some areas of sagebush it approaches 85 percent * plant heights vary between 15 cm and 122 cm * main plants are deciduous, most having spiny leaves * widely distributed animals are jack rabbits, kangaroo rats, kangaroo mice, pocket mice, grasshopper mice, and antelope ground squirrels - areas like Utah, population density of these animals can range from 14- 41 individuals per hectare - All except the jack rabbits are burrowers > burrowing habit also applies to carnivores like the badger, kit fox, and coyote. Several lizards do some burrowing and moving of soil. - Deer are found only in the winter.

>> produces the rich soil for the grain growing regions of the world >>> support the world’s food supply * USA - Great Plains or Tall Grass Prairies ex. Bison, burrowing mammals * Africa - Serengeti Plain (Tropical Grasslands of Africa ) ex. Zebra. Ostrich, lions * considered as the transitional biome - grasslands are usually found between the desert and the forest > would become a forest if grasslands received more rain > if it received any less rain, it would be a desert * large areas with rolling hills of grasses and wildflowers * found on every continent but Antarctica * grasslands are also called prairies, savannahs, or steppes * roots of the grasses and small plants make the soil rich and great for farming and animal grazing * extremely hot during the summer months and very cold during the winter months * grasslands receive anywhere from 10-30 inches of rain per year Types of Grasslands 1. Tall grasslands - have very tall grass, up to 5 feet tall - almost 30 inches of rain a year 2. Mixed grasslands - have grasses that grow around 2-3 feet high - about 15-25 inches of rain in a year 3. Short grasslands - almost a desert - has very short grass - receives 10 inches of rain each year Note: True prairies and grasslands are becoming harder and harder to find. People are taming the wild lands, and the grasslands are becoming as extinct as the animals that are missing from them today.

The desert jack rabbit eats plants, such as the cactus. It is very careful to avoid the prickly spines! Its ears pick up any sound of danger. They also help keep the rabbit cool because heat can escape through the tiny blood vessels that are found there.

In Africa, national parks are being set up to preserve the grasslands. The United States is starting to preserve the wild grasslands. It is even replanting grass where it has been cleared for farming.

Camels are the most well known desert animals. They are sometimes called "the ship of the desert" because they can cross the desert better than any other animal. Camels have bushy eyebrows and two rows of eyelashes to keep the sand out of their eyes. Their nostrils can also be closed. The humps on camels' backs do not hold water as commonly believed. Instead they store fat reserves that can be broken down into food when crossing the desert. The hump will shrink if a camel is starving.

Savannah - a grassland with scattered trees - Americas = grazed by cattle ; Bisons (before) - Australia = cattle, sheep, kangaroo, small rodents - Africa = African elephant, lions, zebras, giraffe, lions, tigers, black rhinoceros, cheetahs, and insects

GRASSLANDS * average rainfall is about 125-75 cms (10-30 in) per year > not enough water fro trees but sufficient for grasses * natural pastures for grazing animals * natural grasses hold the soil through their spreading roots > grasses die and decompose > accumulates organic materials

FRESHWATER AND MARINE BIOMES * Freshwater and marine biomes are probably the most important of all the biomes * medium – water - a major natural resource - the basis of life - supports life, growth, and reproduction - countless species live in it for all or part of their lives * Freshwater biomes supply us: our drinking water water for crop irrigation

* the world's oceans have an even greater effect on global climate than forests do > water has a high capacity for heat > because the Earth is mostly covered with water > temperature of the atmosphere is kept fairly constant and able to support life (climate-buffering capacity) * oceans contain several billion photosynthetic plankton which account for most of the photosynthesis occurring on Earth > without these, there might not be enough oxygen to support such a large world population and complex animal life. * includes lakes, rivers, streams, ponds, inland swamps, springs, and rivers * planktons in the still waters of lakes ands ponds do not survive the running waters of streams and rivers * Biotic and abiotic factors: 1. strength of current and type of bottom 2. differences in water temperature Freshwater biome A lake at Acadia National Park, Maine. * Freshwater - defined as having a low salt concentration > usually less than 1% * plants and animals in freshwater regions are adjusted to the low salt content and would not be able to survive in areas of high salt concentration (i.e., ocean) * Different types of freshwater regions: 1. Ponds 2. Lakes 3. Streams 4. Rivers 5. Wetlands Ponds and lakes * range in size from just a few square meters to thousands of square kilometers > a pond is a body of water smaller than a lake * scattered throughout the earth, several are remnants from the Pleistocene glaciation * many ponds are seasonal, lasting just a couple of months (such as sessile pools) * lakes may exist for hundreds of years or more * ponds and lakes may have limited species diversity since they are often isolated from one another and from other water sources like rivers and oceans * lakes and ponds are divided into three different “zones” which are usually determined by depth and distance from the shoreline 1. Littoral zone 2. Limnetic zone 3.Profundal zone Littoral zone * the topmost zone near the shore of a lake or pond * warmest zone - shallow and can absorb more of the Sun's heat * sustains a fairly diverse community: several species of algae (like diatoms rooted and floating aquatic plant grazing snails, clams, insects, crustaceans, fishes, and amphibians

* insects ( dragonflies and midges) > only the egg and larvae stages are found * vegetation and animals living in the littoral zone are food for other creatures such as turtles, snakes, and ducks Limnetic Zone * near- surface open water surrounded by the littoral zone * well-lighted (like the littoral zone) and is dominated by plankton, both phytoplankton and zooplankton Planktons - small organisms that play a crucial role in the food chain - without aquatic plankton, there would be few living organisms in the world, and certainly no humans - a variety of freshwater fish also occupy this zone > plankton have short life spans > when they die > they fall into the deep-water part of the lake/pond, the profundal zone Profundal Zone * zone is much colder and denser than the Littoral and Limnetic Zones * little light penetrates all the way through the Limnetic zone into the Profundal zone * fauna are heterotrophs > they eat dead organisms and use oxygen for cellular respiration * temperature varies in ponds and lakes seasonally - summer: the temperature can range from 4° C near the bottom to 22° C at the top - winter: temperature at the bottom can be 4° C while the top is 0° C (ice) * in between the two layers, there is a narrow zone called the thermocline where the temperature of the water changes rapidly during the spring and fall seasons > there is a mixing of the top and bottom layers, usually due to winds, which results in a uniform water temperature of around 4° C > mixing also circulates oxygen throughout the lake * many lakes and ponds that do not freeze during the winter > top layer would be a little warmer. Streams * a.k.a. brook, beck, burn, creek, crick, kill, lick, rill, river, syke, bayou, rivulet, or run * bodies of flowing water moving in one direction * streams and rivers can be found everywhere * get their starts at headwaters, which may be springs, snowmelt or even lakes > travel all the way to their mouths > usually another water channel or the ocean * characteristics of a river or stream change during the journey from the source to the mouth Source: cooler temperature clearer water higher oxygen levels freshwater fish such as trout and heterotrophs can be found

Middle: the width increases, as does species diversity > numerous aquatic green plants and algae can be found Mouth: water becomes murky from all the sediments that it has picked up upstream > decreasing the amount of light that can penetrate through the water > since there is less light > less flora diversity > because of the lower oxygen levels, fish that require less oxygen, such as catfish and carp, can be found Wetlands * area of land consisting of soil that is saturated with moisture ex. swamp, marsh, bog * in terms of physical geography, an environment "at the interface between truly terrestrial ecosystems and aquatic systems making them inherently different from each other yet highly dependent on both“ > essentially, wetlands are ecotones * often host considerable biodiversity (highest) and endemism * areas of standing water that support aquatic plants * plant species adapted to the very moist and humid conditions are called hydrophytes ex. pond lilies, cattails, sedges, tamarack, and black spruce * marsh flora: cypress and gum * fauna: amphibians, reptiles, birds (such as ducks and waders), and furbearers * not considered freshwater ecosystems, such as salt marshes > have high salt concentrations > support different species of animals, such as shrimp, shellfish, and various grasses * freshwater biomes have suffered mainly from pollution > runoff containing fertilizer and other wastes and industrial dumpings enter into rivers, ponds, and lakes > tend to promote abnormally rapid algae growth > when these algae die, dead organic matter accumulates in the water > makes the water unusable and kills many of the organisms living in the habitat Note: stricter laws have helped to slow down this thoughtless pollution * overfishing and pollution have threatened to make oceans into ecological disaster areas! * educating people about the consequences of our actions, we can all gain a better understanding of how to preserve the Earth's natural biomes Note: The areas that have been destroyed the most will never regain their original forms,but conservation will help to keep them from getting worse! Marine biome * marine regions cover about three-fourths of the Earth's surface * include oceans, coral reefs, and estuaries

* marine algae: supply much of the world's oxygen supply take in a huge amount of atmospheric carbon dioxide * evaporation of the seawater provides rainwater for the land OCEANS * largest of all the ecosystems * very large bodies of water that dominate the Earth's surface * average temperature of all oceans is about 39 degrees F (3.8 degrees C) * the oceans in different parts of the world can have very different climates: ex. Tropical oceans - oceans near the equator, are warm and clear on the surface Equator - is an imaginary belt which circles the earth and divides it into two halves - areas of land and water which are near this belt are called the tropics, and are always warm. cold polar regions - the ocean is so cold that its' surface is frozen > huge blocks of ice called ICEBERGS drift in these seas * the sun's heat warms only the surface of the water > deep down, oceans everywhere are cold, dark, and still * over 70 percent of the earth's surface is covered by water * average depth is 3.7 kms (2.2 miles) ; deepest - 11.5 kms (6.9 miles) * like ponds and lakes, the ocean regions are separated into separate zones: 1. Intertidal zone 2. Ocean water - Pelagic zone 3. Ocean bottom/floor - Benthic zone a. Littoral zone b. Deep sea zone 4. Abyssal * all four zones have a great diversity of species > some say that the ocean contains the richest diversity of species even though it contains fewer species than there are on land * average depth of all oceans is about 2.3 miles * there are mountains, volcanoes, and deep trenches in the ocean * oceans are always moving * currents flow like rivers, carrying warm water from the tropics, and cold water from the north and south poles * tides change twice a day, all over the world, as the oceans rise and fall along the shoreline > scientists think this is caused by the pull of the sun and moon on our earth * four main oceans: the PACIFIC, ATLANTIC, INDIAN, and ARCTIC PACIFIC Ocean - largest of the four main oceans - name means peaceful, if can be very rough - It is 64 million square miles

ATLANTIC Ocean - the busiest > many ships cross the Atlantic, carrying cargo between the Americas, Africa, and Europe - It is 32 million square miles INDIAN Ocean - located in an area bordered by the continents of Asia, Arica, Antarctica, and Australia - it is 28 million square miles ARCTIC Ocean - smallest and coldest - it is 5 million square miles Intertidal Zone (Foreshore) * shore area alternately uncovered and covered by water * zone where the ocean meets the land > submerged or exposed, as waves and tides come in and out > because of this, the communities are constantly changing * on rocky coasts, the zone is stratified vertically > where only the highest tides reach, there are only a few species of algae and mollusks * in those areas usually submerged during high tide > more diverse array of algae and small animals, such as herbivorous snails, crabs, sea stars, and small fishes * at the bottom of the intertidal zone, which is only exposed during the lowest tides > many invertebrates, fishes, and seaweed can be found * the intertidal zone on sandier shores is not as stratified as in the rocky areas > waves keep mud and sand constantly moving >> very few algae and plants can establish themselves * fauna: worms, clams, predatory crustaceans, crabs, and shorebirds Pelagic zone (Ocean water) * pelagic comes from the Greek word pélagos, which means open sea * includes those waters further from the land, basically the open ocean * any water in the sea that is not close to the bottom * generally cold (hard to find average temperature range) > just like ponds and lakes, there is thermal stratification with a constant mixing of warm and cold ocean currents * Flora: surface seaweeds * Fauna: many species of fish and some mammals, such as whales and dolphins > feed on the abundant plankton * Flora: primarily by seaweed * Fauna: since it is very nutrient-rich > include all sorts of bacteria, fungi, sponges, sea anemones, worms, sea stars, and fishes * most important abiotic factor: depth of sunlight penetration e.g. 180 meters ( 595 feet) – reaching the pelagic zone > lighted area is the most productive area = abundant nutrients Plankton - basic food in the Pelagic Zone - includes diatoms, dinoflagellates, unicellular algae**, protozoans, and larval forms of animals - many copepods*, small shrimp, jellyfish and worms > copepods feed on microscopic algae

>> copepods are eaten by small shrimps ( krill ) >>> krill is the major food of the whale *** unicellular algae = most important food producer in the ocean Benthic zone (Ocean bottom /floor) * area below the pelagic zone although it does not include the very deepest parts of the ocean (see abyssal zone below) * bottom of the zone consists of sand, silt, and/or dead organisms * temperature decreases as depth increases toward the abyssal zone > since light cannot penetrate through the deeper water * Flora: primarily by seaweed * Fauna: since it is very nutrient-rich > include all sorts of bacteria, fungi, sponges, sea anemones, worms, sea stars, and fishes Benthos - the organisms which live in the benthic zone, and are different from those elsewhere in the water column - many are adapted to live on the substrate (bottom) - most organisms in the benthic zone are scavengers or detritivores Abyssal zone * the deep ocean * water in this region: very cold (around 3°C) highly pressured high in oxygen content low in nutritional content * supports many species of invertebrates and fishes * mid-ocean ridges (spreading zones between tectonic plates), often with hydrothermal vents, are found in the abyssal zones along the ocean floors > chemosynthetic bacteria thrive near these vents because of the large amounts of hydrogen sulfide and other minerals they emit >> these bacteria are thus the start of the food web as they are eaten by invertebrates and fishes Oceans * animals below the light penetrating region get their food from: a. sinking plankton b. dead animals c. swimming animals passing between the two levels *deep sea bottom feeders : falling food from above bacteria present in the ooze of the ocean bottom > break up dead organisms in the bottom * mineral exchanges in the ocean occur due to currents and upwellings > changes in water temperature >> cause deeper waters to rise to the surface periodically Upwellings > bring colder waters to the surface > bring minerals and essential substances to the surface >> marine life are attracted to area due to food abundance

>>> sustainable fishing areas Depth and layers * Depending on how deep the sea is, there can be up to five vertical layers in the ocean 1. Epipelagic (sunlit) - From the surface down to around 200 meters (656 ft) - the illuminated surface zone where there is enough light for photosynthesis > plants and animals are largely concentrated in this zone - nearly all primary production in the ocean occurs here - this layer is the domain of fish such as tuna, many sharks, dolphin fish, and jellyfish 2. Mesopelagic (twilight) - 200 meters down to around 1,000 meters (3,280 ft) - some light penetrates but is insufficient for photosynthesis - at about 500 meters, the water becomes depleted of oxygen > animals with more efficient gills or minimal movement survive - Fauna: swordfish, squids, wolf fish, a few species of cuttlefish, and other semi-deep-sea creatures live here Bathypelagic (dark) - from Greek bathýs, meaning deep - from 1,000 meters down to around 4,000 meters (13,123 ft) - by this depth, the ocean is almost entirely dark (with only the occasional thermoluminescence organism, such as the lanternfish - there are no living plants, and most animals survive by consuming the snow of detritus falling from the zones above or (like the marine hatchetfish) by preying upon others - giant squid, as well as smaller squids and Dumbo octopuses live at this depth > hunted by deep-diving sperm whales Abyssopelagic - from the Greek ábyssos, abyss, meaning bottomless - From 4,000 meters down to above the ocean floor - no light whatsoever penetrates to this depth Hadopelagic - the deep water in ocean trenches > waters below 6,000 m (19,685 ft), whether in a trench or not. - derived from the Greek (Haidēs), Hades, the classical Greek underworld - zone is mostly unknown - very few species are known to live here (in the open areas > many organisms live in hydrothermal ventsin this and other zones - some define the hadopelagic and other zones very similar in character, or marine biologists combine them into a single zone or consider the latter two to be the same. Coral reefs * vast, rocky areas located in warm, shallow, tropical waters > the tropical rain forest of the ocean >> where the greatest variety of plant and animal life in

the ocean live * found as barriers along continents ex. Great Barrier Reef off Australia, fringing islands, and atolls * naturally, the dominant organisms in coral reefs are corals Corals - consist of both algae (zooanthellae) and formed from tissues of small sea animals / creatures called polyps * reef waters tend to be nutritionally poor > corals obtain nutrients through the algae via photosynthesis > by extending tentacles to obtain plankton from the water * besides corals, the fauna include several species of microorganisms, invertebrates, fishes, sea urchins, octopuses, and sea stars Estuaries * areas where freshwater streams or rivers merge/flow with the ocean (sea) > mixing of waters with such different salt concentrations creates a very interesting and unique ecosystem * zone between the freshwater and marine biomes * nurseries for many young fishes, crustaceans and shellfishes * Flora: microflora like algae macroflora, such as seaweeds, marsh grasses, and mangrove trees (only in the tropics) * Fauna: support a diverse fauna, including a variety of worms, oysters, crabs, and waterfowl Polar Biomes A. Antarctica ( South Pole) - very large continent - USA and Canada combined - The name Antarctica is a romanized version of the Greek compound word Αntarktikí meaning "opposite to the north” - the coldest, driest and windiest continent has the highest average elevation of all the continents > there is little precipitation, except at the coasts >> the interior of the continent is technically the largest desert in the world - no permanent human residents - only cold-adapted plants and animals survive Fauna: penguins, fur seals Flora: mosses, lichens and many types of algae * covered by ice ; average ice depth = > 1km long ( 0.6 miles) - more than 90% of the world’s ice found here - Antarctic’s winds measure at more than 300 kms (180 miles) / hour - mean temperature does not go above freezing at any time > water is always frozen South Pole * vegetation: only 3 flowering plants exist at the tip of the peninsula > lichens and moss are rare >> lack of food producers * fauna: few animals are present ex. penguins, few migrating birds, mites, wingless fly, rare insects ** 50% of these small invertebrates are parasites supplied by

the pelagic marine biome surrounding Antarctica B. North Pole * also known as the Arctic * word Arctic comes from the Classical Greek word arktos which means bear > name refers to the constellation Ursa Major, the "Great Bear", which is prominent in the northern portion of the celestial sphere * smaller landmass than Antarctica and spread out in several continents > sometime some Tundra biome extends to it * ice sheet covering = about 5 meters thick (16.5 ft.) * average Arctic temperature = 17C (62.6F) - >25C (77F) * 90% of its landmass loses its ice during summer > supply water to plants * about a million people live here e.g. Eskimos and reindeer herders from North America, Europe, Asia and Greenland * vegetation: more than 100 flowering plants identified aside from mosses and lichens * animals: polar bears, arctic foxes, insects, birds, and other mammals > derive their food from the pelagic marine biome, as in Antarctica _________________ BIOLOGICAL COMMUNITIES (Plant and Animal Communities) ECOSYSTEM - synonymous with biological communities, EXCEPT that it includes the non-living or physical environment of the community.

Ex. consocies, associations, formations 2. Habitat - popular term - environmental complex occupied by a particular kind of organism, or by a single community of organisms Example of hierarchies: lake - a large ecological unit > smaller units of beach communities, shallow margins, deep bottom, and the open water >> marginal communities >>> special communities associated with water surface, certain plant species, or with bottom mud Ecological communities adopted by biologists: Ex. aquatic series - plankton, neckton, and benthos Plankton - “ wandering” - numerous and diverse in the sea and fresh water - in the oceans, forms the basis for the whole economy Neckton - larger, free swimming organisms ex. Fish Benthos – organisms that live on or in the bottom * To define a community in terms of a “dominant” and a “sub-dominant” species a. Temperate terrestrial habitats - a particular savannah grass or a tree species in the forest may dominate b. Tropical or aquatic habitat - concepts of dominance is insignificant

Terms and definitions

Interaction between biotic and abiotic factors in a lake ecosystem: * green plants MUST grow near the water surface to receive the sun’s rays * depth, stirred-up mud, heavy algae growth, ice/snow limits light penetration > no photosynthesis * clear lake water enables the sun’s rays to penetrate up to 25 m(82.5 ft) deep * remains and accumulated debris of dead plants and animals > may reduce lake size * daily or seasonal variation of water temperature > affects organisms * conditions like rain runoffs > carry plant/animal debris and soil to the lake * biotic community member like man > dumping, destroying, playing >> affects the ecosystem

Biotic Community - organisms living and acting in an ecosystem Population - group of organisms of the same species living in an ecosystem Physical Environment - Refers to the non-living part of the ecosystem

Interaction among physical factors in a lake ecosystem: * either temporary or permanent changes * factors / conditions affecting the lake ecosystem (either gradual or rapid) cloud covers ; silt carried from runoffs ; daily / seasonal temperature chemicals from fertilizers of man or wastes from factories ; water levels

Classification of Communities – no universal acceptance 1. Biocoenosis - technical term for a single community graded into complex hierarchies

Succession of Communities: Regular series of changes in the growth or aging of a community or a series of communities

- smaller unit of the biosphere where living and non-living things interact and where materials can be recycled. - smaller units of interacting biotic and abiotic factors in the biomes and are dependent on each other ex. light,oxygen,CO2, growing space, minerals, temperature, and most importantly, ENERGY. Examples: lakes, rivers, ponds, meadows * vegetation / plant communities are more pronounced > vegetation is basic in any study of intra-communal relationships

> constant > series of human disturbances and geological processes > altered landscapes >> slow and regular succession of communities >>> relatively stable and unchanging conditions >>>> “climax forest” >>>>> repetition of cycle * areas with lesser human depredation > succession is real but less obvious ex. landslide > bares the cliff surface ; a tree falls in the forest >> beaches, rivers - may become deposition areas NUTRITIONAL RELATIONSHIPS IN AN ECOSYTEM Terms: FOOD CHAINS - better term > FOOD WEB - important relationship within a community - the sequence of organisms through which energy and materials are passed as the organisms eat or are eaten - many overlap > organisms eating more than one type of food FOOD WEB - the complex of interlocking food chains in almost all communities TROPHIC LEVEL - the position of an organism in a food chain PRODUCTIVITY - the accumulation of energy - only the accumulated energy is available to the next trophic level ex. productivity of the herbivore is 15% of the energy it has taken from the plants AUTOTROPHS - aut, auto = self ; trophos = one who feeds - organisms that make their own food from inorganic nutrients and energy from the sun ex. Cattails, duckweeds, algae - food producer of the ecosystem ; important resource HETEROTROPHS - hetero = other, different ; trophos = one who feeds - organisms that obtain their food by eating plants and other animals - all are food consumers > divided onto several trophic levels PHYTOPLANKTON - phyton = tree, plant ; plankton = wandering - refers to the suspended microscopic algae serving as food for the small crustaceans ex. ostracods and copepods TROPHIC PATTERN - transfer of energy form the autotrophs to the herbivores and through several levels of carnivores ex. starts always with the producer > first-level carnivore, and so forth HERBIVORES - herba = grass, green crops ; voro = devour or eat - heterotrophs or any organisms feeding on plants > FIRST FOOD CONSUMER

- energy is used when it moves, eats, digests, respires, and reproduces > most of the energy in its food is not stored >> used up to maintain life’s processes ex. copepod – uses 85% of the energy for maintenance ; 15% is stored CARNIVORES - carnis = flesh ; voro = devour or eat - animals feeding on other animals ex. minnows feeding on small crustaceans = first-level carnivore * First-level carnivore – feeds on herbivores > 15% of the energy taken in – 15% of 15% = 2.25% is available to the next trophic level ( represents the original energy produced by the green plant) *bass feeding on minnows = second-level carnivore > energy in the bass - 0.3375% of the original energy produced by the green plant Lake ecosystem : more than one food chain if no other animal eats the bass > bass = top carnivore ; except for man > if the bass dies = crayfish eats it >> bullfrog or raccoon eat crayfish *young fishes feeding on both herbivores or minnows > not considered either as first or second-level carnivores OMNIVORES - omnis = all ; voro = devour or eat - animals that eat both plants and animals - do not confine their feeding habits to one trophic level ex. man SCAVENGERS - organism that feeds on dead organisms - important in the recycling of chemicals - transfer the energy to the animals that feed on them ex. crayfish, snails, some fishes DECOMPOSERS - breakdown tissues and wastes of organisms into simpler substances > return nitrogen, phosphates etc. to the soil or water >> without them, bacteria cannot recycle them to ecosystem >>> autotrophs can use them to restart another cycle Decay - process of breaking down tissues / wastes of organisms into simpler substances ECOLOGICAL PYRAMIDS * normally seen in nutritional relationships * BASE = food producers ; TIP = top carnivore Three common models: 1. Pyramid of Productivity 2. Pyramid of Numbers 3. Pyramid of Mass Pyramid of Productivity

- trophic structure of the food chain based on the energy passed on from one trophic level to another ex. sun’s energy > algae ( BASE ) > copecods (15%) > minnows (2.25%) > bass (0.3375% ; TIP) Pyramid of Numbers - trophic structure of the food chain based on the number of individuals involved in each trophic level of the food chain - helps us to understand the energy relationships in ecosystems and predict future changes ex. hectare of field - food producers = 5M herbivorous invertebrates = 700,000 * food for about 300,000 ants, spiders, and predatory beetles * average of 3-5 birds and 3 mammals on top > tree > caterpillar > bird > hawk Pyramid of Mass * gives us a clearer picture of biotic relationships * determines the mass of each link ; pyramid of mass - actual pyramid ex. in a selected area – all organisms are weighed and separated > trees are lesser than caterpillars >> ONE tree can support many caterpillars >>> mass of the tree is greater than the mass of the caterpillars * tree > caterpillar (BASE) > birds > hawk (TIP) Food Pyramids - may help solve man’s social problem Hunger? Population? * sun’s energy in each food level – most are loss during transfer - about 85% due to respiration, growth, excretion, heat, and movement * man should position themselves here and become herbivores than first or second-level carnivores > more food energy found >> larger population can be fed from the same amount of original energy from the sun SPECIAL NUTRITIONAL RELATIONSHIPS * most heterotrophs are bulk feeders Bulk Feeders - eat the whole or parts of the organisms * most heterotrophs are called saprophytes Saprophytes - absorb nutrients from dead tissues or waste products from organisms - includes bacteria that decompose plant and animal bodies, fungi, and yeasts - vital in returning materials to the ecosystem SYMBIOSIS ( MUTUALISM ) * biotic relationship in which two species (symbionts) live in close association with one another ; may or may not be nutritional ex. orchids growing on trees on a tropical forest (limited space/ sunlight) > no food is given but more exposed to sunlight than in forest floor ruminants (cellulose-eater), horses, and

their intestinal bacteria which partially digests raw food materials Three Types of Nutritional Symbiosis 1. Parasitism - a relationship in which one organism obtain its nutrition at the expense of another organism. ex. Intestinal worms, ticks , fleas - limited to forms belonging to the animal kingdom > aptly termed animal parasites - disturbs physiologic activities > causes tissue destruction and/or damage - consistent feature: alters the chemical and physical composition of the blood > some are beneficial to the hosts = produce antibodies ex. agglutinins, precipitins, and opsonins > some are detrimental = produce anemia, leucocytosis, leucopenia Characteristics of Parasitism: a. provides a certain degree of danger to the host b. maintain a more or less constant and close association between the host and parasite c. a complete dependence on food produced by the host, either in the form of digested substances and tissues 2. Mutualism - a relationship between two species in which both benefit from living together. ex. birds picking on a a carabao’s back hermit crab ( transports the sea anemones to new feeding grounds) while the sea anemone (camouflages / hides/ protects the crab with its poisonous tentacles) 3. Commensalism - or neutral parasites - a relationship in which one organism benefits (commensal) and the other neither benefits or is harmed (host) ex. intestinal protozoa, bacteria (E. coli*) of man * may become pathogenic under certain conditions - may be in the: internal organs ( endocommensalism) body surface like hair, skin > ( ectocommensalism / epicommensalism) - seen in some bacteria species ex. bacteria species A cannot use a certain potential food > needs bacteria species B, if present, to breakdown the food material and produce compounds that can be used by bacteria species A >> growth occurs Structure of Biotic Communities 1. Biotic community is made up of organisms living together and interacting Predation - interactions between organisms on different trophic levels - involves predator and prey Competition - interactions on the same trophic level - the use of or defense of a resource by one individual that reduces the availability of that resource to other animals

ex. hawk catches/ eats mice = less one mouse for other hawks - does not always involve the same species ex. if the hawk was successful > one less mouse for the owls to eat - competition may be indirect ex. hawk and owl > feed at different times ; eat a variety of different foods * competition is more pronounced and severe among member of same species > seeks the same resources and have the same needs 2. Scarce resources - the number of individuals of a species living in a community will be limited ex. barnacles in the intertidal zone = other barnacles require the same space > a larval barnacle attaches itself onto a a sparsely populated rock and grows into an adult > limited space on the rock if a rock is fully covered > larva attaches itself into the shell of another animal >> grows rapidly and kills the other animal in the process >>> occupies its space, grows rapidly for a while, then dies 3. An animal’s behavior may reduce competition - a single resource can serve to support several populations in a community ex. birds feeding on insects in a forest > feed at different levels in the trees Patterns Within a Biotic Community A. Rhythms Diurnal - an animal that is active during the day Nocturnal - an animal that is active at night Crepuscular - an animal that is active at dusk and dawn