The six basic animal groups include mammals, birds, reptiles,fish, amphibians and invertebrates. There are also other groups ofanimals, and the way scientists classify and categorize themchanges frequently.

MAMMALSMammals are warmblooded animals thatmaintain their owninternal body tem-perature. They havehair, breasts and asingle bone lowerjaw. They are verte-brates, meaning theyhave a backbone.Mammal groups in-clude primates, car-nivores, elephants,anteaters, rodents,rabbits, bats, marsu-

pials, seals, cetaceans, odd-toed ungulates and even-toed ungu-lates. Mammals have a diaphragm, a four-chambered heart andthree middle ear bones.

BIRDSBirds are feath-ered, winged,two-legged,warm blooded,egg-laying ani-mals with back-bones. Wings areevolved fore-limbs, and mostbird species canfly. Some birdscan swim. Birds include birds of prey, perching birds, humming-birds, owls, gamebirds, flamingos, pigeons and doves, pelicansand penguins.

REPTILESReptiles are coldblooded animalswith backbones, in-cluding turtles, croc-odilians, snakes,lizards and tuatara.They are differentfrom amphibians inthat they have scales

and lay hard-shelled eggs. Reptiles have four limbs or, likesnakes, are descended from four-limbed ancestors. Unlike am-phibians, reptiles do not begin their lives in the water.

A WORLD OF ANIMALSAMPHIBIANSAmphibians – like fishes,mammals, birds, and reptiles– have backbones. Newts,salamanders, frogs, toadsand caecilians are amphib-ians. They are also tetra-pods, meaning they havefour legs. They are coldblooded and go through anaquatic childhood stagebreathing with gills as ba-bies, then with lungs asadults. Unlike reptiles,they require water forbreeding.

FISH

Fishes include the bony fishes, cartilaginous fishes, hagfishesand lampreys. They breath through gills, have backbones butno limbs and most are cold blooded. Fish account for morethan half of vertebrate species. Well adapted for the aquaticworld, they usually have streamlined bodies for rapid swim-ming, extract oxygen from water using gills, have fins, jawsand scales, and lay eggs.

INVERTEBRATES

Invertebrates are cold blooded animals that do not have back-bones, including insects, worms, octopuses, crabs, lobsters,snails, clams, starfish and sea-urchins. The overwhelming ma-jority of animal species are invertebrates. They do not have askeleton of bone, either internal or external. Some have fluid-filled skeletons, like jellyfish or worms. Others have hard exo-skeletons, outer shells, like insects and crustaceans. There areso many types of invertebrates that few key characteristics canbe ascribed to all of them.

WORLD ANIMAL FOUNDATION®

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● Temperate Forests are in temperate regions of theearth including North America, Europe and Asia.They have four well-defined seasons and a growingseason between 140 and 200 days. Rainfall takes placethroughout the year and soils are nutrient-rich.

● Tropical Forests are located in equatorial regionsbetween 23.5°N and 23.5°S latitude. They experiencetwo seasons, a dry season and a rainy season. Thelength of each day varies little throughout the year.Soils in tropical forests are nutrient-poor and acidic.

● Boreal Forests make up the largest terrestrial habitat.They are a band of coniferous forests located in thehigh northern latitudes between about 50°N and 70°N.Boreal forests create a circumpolar band of habitatfrom Canada, to northern Europe, to eastern Russia.They are bordered by tundra habitat to the north andtemperate forest habitat to the south.

Some of the wildlife that inhabit the forest biome includedeer, bears, wolves, moose, caribou, gorillas, squirrels,chipmunks, birds, reptiles and insects.

AQUATIC WORLDSThe aquatic biome includes habitatsaround the world dominated by water.Aquatic ecosystems are divided into twomain groups based on their salinity—freshwater habitats and marine habitats.

● Freshwater habitats are aquatic habitatswith low levels of salt, less than one percent.They include rivers, lakes, streams, ponds,swamps, wetlands, bogs and lagoons.

● Marine habitats are aquatic habitats withsalt concentrations of more than one percent.They include oceans, seas and coral reefs.

Some habitats exist where saltwater and freshwatermix together. These include mud flats, mangrovesand salt marshes. Aquatic ecosystems support a di-verse assortment of animals including fishes, am-phibians, reptiles, mammals, birds and invertebrates.

WOODED WORLDSForest biomes are dominated by trees and extendover one-third of the earth's land surface. There arethree main types of forests—temperate, tropical and boreal. Eachtype has a different assortment of animals, climate characteristicsand species compositions.

Biomes, or ecosystems, are large regionsof the planet with shared characteristicssuch as climate, soils, plants and animals.Climate is an important factor that shapesthe nature of an ecosystem, as well as pre-cipitation, humidity, elevation, topographyand latitude. The five major biomes in-clude aquatic, desert, forest, grassland andtundra biomes. Each biome also includesnumerous types of sub-habitats.

HABITATS: WORLDS WITHIN OUR WORLD

LANDS OF GRASSGrasslands habitats are dominated by grasses with few largeshrubs or trees. The three main types of grasslands include tem-perate grasslands, tropical grasslands or savannas and steppegrasslands. Grasslands have dry seasons and rainy seasons. Theyare susceptible to fires during dry seasons.

● Temperate Grasslands have a lack trees and largeshrubs and are dominated by grass. The soil has an upperlayer that is nutrient-rich. Seasonal droughts result infires that keep trees and shrubs from taking over the area.

● Tropical Grasslands are located near the equator withwarmer, wetter climates than temperate grasslands andmore pronounced seasonal droughts. They are dominatedby grasses, but also have scattered trees. The soil of tropi-cal grasslands are porous and drain quickly. Tropicalgrasslands can be found in South America, Australia, Af-rica, India and Nepal.

● Steppe Grasslands are dry grasslands that border onsemi-arid deserts. Their grasses are much shorter thantemperate and tropical grasslands and they lack trees ex-cept along rivers and streams.

Animals that inhabit grasslands include American bison, Africanelephants, lions and spotted hyenas.

DRY WORLDSDesert biomes receive very little rainand cover about one-fifth of the plan-et's surface. They are divided into foursub-habitats based on their location,aridity, climate and temperature: ariddeserts, semi-arid deserts, coastal des-erts and cold deserts.

● Arid Deserts are hot and dryand are located at low latitudesthroughout the world. Temper-atures are warm all year andhottest during the summer.Arid deserts receive little rain-fall, and most rain that doesfall usually evaporates. Ariddeserts are located in NorthAmerica, South America, Cen-tral America, Africa, Australiaand Southern Asia.

● Semi-arid Deserts are usually not as hot and dry asarid deserts. They have long, dry summers and coolwinters with some rain. Semi arid deserts are found inNorth America, Europe, Asia, Newfoundland andGreenland.● Coastal Deserts are usually located on the western

edges of continents at approximately 23°N and 23°Slatitude, the Tropic of Cancer and the Tropic of Capri-corn. Cold ocean currents run parallel to the coast,producing heavy fogs. Despite high humidity in coast-al deserts, it rarely rains.● Cold Deserts have low temperatures and long winters

and are found above the treelines of mountain rangesand in the Arctic and Antarctic. They experience morerain than other deserts. Many locations of the tundraare cold deserts.

Desert animals include coyotes, kangaroo rats, spiders, meer-kats, roadrunners, reptiles, toads, snakes, pronghorn, birds andbats.

FROZEN WORLDS

Tundra is a cold habitat with long winters, low temperatures,permafrost soils, short vegetation, brief growing seasons andlittle drainage. The Alpine tundra exists on mountains around

the planet at elevations above the tree line. TheArctic tundra is near the North Pole, extendingsouthward to where coniferous forests grow.● Arctic Tundra in the Northern Hemisphere isbetween the North Pole and the boreal forest. Inthe Southern Hemisphere it exists on remoteislands off the coast of Antarctica and on theAntarctic peninsula. The Arctic and Antarctictundra are home to over 1,700 species of plantsincluding grasses, mosses, sedges, lichens andshrubs.● Alpine Tundra is a high-altitude ecosystemlocated on mountains around the earth at eleva-tions above the tree line. Alpine tundra soils arewell drained compared to tundra soils. Alpinetundra is home to small shrubs, dwarf trees, tus-sock grasses and heaths.The tundra is home to the arctic fox, wolverines,polar bears, northern bog lemmings, muskox,arctic terns, muskoxen and snow buntings.