Temperate GrasslandBefore the arrival of agriculture, the grasslands ofthe Northern Hemisphere were covered with endless

prairies. Far from the moderating influence of the oceans,these areas experience hot summers and long, cold winters.Curiously, in contrast with the prolific leaves typical of plants in other biomes, grassland plants have prolificroots. The roots help store nutrients incase of drought or fire. In additionto being a rich source of food,the roots keep the soil firm.The firm soil allowsrodents to develop anextensive network ofunderground burrows.

SavannaIn the tropical climates of the Southern Hemisphere, grasslands are characterized by a landscape made up of a

few scattered trees (such as the African acacia, a key source of food).Grazing elephants help the acacia to distribute its seeds. Eaten seedsappear in the dung of elephants. Some animals, however, hinder the acacia’s growth by nibbling on its shoots before they can develop. Many treeson the savanna have an umbrella-like shape, as a result of the “trim” theyreceive from giraffes. The savanna is hot all year round, in contrast to thetemperate grassland, and its rainy season is followed by a long dry sea-son. During this time, many animals needto travel long distances to find foodand water.

The landscape of a grassland provides few hiding places, and manyanimals opt to live in a herd to reduce the chances of becoming injured in attacks by predators. Some animals of the herd feed, whileothers remain alert. In the 19th century, herds of gazelles in southernAfrica gathered together in numbers of more than 10 million, a number comparable to the size of the bison herds that once roamed

the North American prairie. Because an individual’s risk ofseparation from the herd is high, many species

have glands in their hooves that produce an odorous substance. This substance will lead the

lost member back to the herd.

Life in Herds

GrasslandI

n both temperate and tropical climates, there are great open expanses covered with grasses. They create an ideal habitat for herbivores such

as bison and rodents. The stalks of grass growing from ground level are adapted to animal grazing. The presence of fast-running predators, the lack of hiding places, and the risk of drought and fires, however, make grasslands a challenging environment in which to survive.

AFRICAN ELEPHANT

Loxodonta africanaThe male elephant is the largest living landanimal. It lives for about60 years. Its trunk hastwo prolongations thatare used for picking upobjects. One function ofits curving tusks is to digup the soil to extract theextra salt that it needs forits diet.

BURCHELL’S ZEBRA Equus burchelliThis animal has a wide field of vision and acute hearing. Its stripes providecamouflage; however, it is thought that they may also regulate temperature orserve a social function that helps individual animals recognize each other. To helpverify the odor given off by females when they are ready to mate, the male

enhances the sensitivity of his sense of smell by lifting his upper lip.

RED KANGAROOMacropus rufusThis animal is the largestliving marsupial. It uses its

highly developed sense ofsmell to find water. In addition,

it has a heavy tail that it usesas a pendulum. Together with its

energy-storing tendons, the redkangaroo can spring forwardwhen it runs. When red kangaroos play or fight amongthemselves, they can stand ontheir hind feet and either kick

or act as if they are boxing.Young kangaroos are born at a relatively

early stage of development. They are nourishedthrough one of the mother’s teats inside a protective pouch. The baby kangaroo does not leave the pouch permanently until some200 days later.

LION Panthera leola Like all cats, the lion has acute senses. Its largeeyes are positioned toward the front of its faceso that it can estimate distances precisely. Its pupils are adapted for excellent night vision.

Its funnel-shaped ears are designed to perceive the soundsemitted by its prey. It also has anorgan above the roof of its mouth,called a Jacobson’s organ, whichassists in the detection of sexual

odors. A distinctive feature ofmale lions is a thick mane.

The mane makes malesappear larger.

GIRAFFE

Giraffa camelopardalisThe giraffe’s unique anatomy allowsfor it to graze the leaves of treesalmost 20 feet (6 meters) high.Despite its long neck, the giraffe, like other mammals, has seven cervical vertebrae. It uses its longtongue, which can extend some 18inches (45 cm), to reach acacia

branches, while its lobulated teethrake off the leaves. There are

regional variations in the pattern of its spotted skin,

and these patterns are useful in the identification

of the nine subspecies,including the reticulated

giraffe. The malesestablish a

dominance hierarchy by striking eachother with theirnecks. Giraffeskulls are reinforced with

an extra bone.

Grass contains large amounts of cellulose,a carbohydrate that is difficult to digest.Some animals, such as the giraffe, are ableto break it down with the help of enzymesproduced by their stomach bacteria.

Cellulose

Given the presence of very fast predators, running is a good means of escape for prey.Many mammals can run fast, but certainbirds that do not fly (ostriches, emus, andñandus) can, too—at speeds up to 45 miles(about 70 km) per hour. These flightlessbirds can maintain this speed for 30 minutes!The birds also make use of their height andlarge eyes to spot possible predators fromlong distances away. In contrast, slower prey animals often seek refuge in burrows.

Winner in Speed

BLACK-TAILED PRAIRIE DOGCynomys ludovicianusThis rodent, which makes its homein grasslands, emits a howl similarto that of a dog. It is a social animal, and it is known for the interconnected burrowsthat it digs. Prairiedogs also form subgroups for protectionfrom predators.

EMU Dromaius novaehollandiaeThis large bird—the largest in Australia—can grow to aheight of 6.5 feet (2 meters). Its feet have three toes thatare adapted for running. Although it has lost the ability tofly, it is a fast runner and swimmer. It is covered with afleecy plumage that insulates it from the Sun’s rays. Afterthe chicks hatch from their eggs, the male emu cares forthem until they reach eight months of age.

125 miles(200 km)the distance kangaroos sometimes travel in search ofwater during the dry season

34 MAJOR BIOMES OF THE WORLD ECOLOGY 35

Termite MoundsThese incredible hills, which take termitesbetween 10 and 50 years to build, serveas protection from predators and the hotclimate. The termite colony begins with achamber about 12 inches (30 cm) deep, a location in which the king and queenmate. The termites that hatch from the

eggs are charged with constructingthe mound. Walls built from bits of wood are mixed with excrement to form irregular, arched rooms. A sophisticated system of tunnels and chimneys provides ventilation and cooling.

TERMITE Isoptera

Social insects, termites live in immense colonies. Termites take dead plant matter totheir nests, where they cultivate the fungi onwhich they feed. They can digest wood with thehelp of microorganisms that live in their intestines.

Herbivoresand Predators

The abundance of grasses andother plants in the savanna

leads to the presence of a great varietyof animals that graze on them. Whilezebras and buffalos feed on the tallest shoots, gnus and gazelles graze on the lowerleafy layers. Ruminants (such as the antelope,buffalo, and giraffe) have microorganisms in theirdigestive tracts that decompose the cellulose ofgrass. The herbivorous inhabitants of the savanna serveas food for predators (such as the lion, leopard, andhyena). A notable predator is the cheetah, which is knownfor its rapid sprints. Other animals on the savanna includecarrion-eaters, such as various species of eagles and vultures that fly in circles to locate the bodies of dead animals.

African SavannaT

he most extensive savanna in the world lies in Africa. In contrast with theNorth American prairie, the grassy areas of the savanna are mixed with afew shrubs and trees, such as acacias and baobabs.

The herbivores that feed on them (such as giraffes, rhinoceroses, antelope, and elephants) avoid the competition for food by eating at different levels. The alternation between wet and dry seasons brings about astonishing migrations of animals that raise largeclouds of dust in their passage.

COEXISTENCEThe stems of grasses as well as other plantssprout from the ground’s surface. In some species, plants begin well below ground. As a result, most plants are not destroyed by the animals that graze on them.

ILLEGAL HUNTINGOnly about 7,000 rhinoceroses remain. The animal is pursued by hunters for itshorn, which has a purported medicinal value.

SPEEDThe cheetah can accelerate to 60 miles

(about 100 km) per hour in just five seconds.

HerdsMost of the herbivorous animals on the savanna live

in herds to protect themselves against predatorssuch as lions, cheetahs, and wild dogs. Herds of

zebras can contain as many as 200,000 individuals, whereas herds of wildebeest, or

gnus, can reach 1.5 million in size. In May,with the arrival of the dry season, wildebeest

herds migrate in search of food and waterfrom Africa’s southern grasslands to the eastand north. When the rains begin and grasses

begin to grow again, the herds return. They cancover distances as great as 1,500 miles

(2,500 km) in one year.

ACACIAAfrican species are thesource of gum arabicand gum senegal,which is used to cureskins. The wood ofthe acacia isstrong, heavy,and dense. Itis used com-mercially.

DUNG BEETLEScarabaeidae

This beetle uses thedung produced by thesavanna’s large mam-

mals. It forms thedung into balls into

which it deposits itseggs. The beetle buries the

dung ball, and its larva later feed on it.

SCATTERED TREESUnlike temperate grasslands,

which are completely open lands,savannas have a mixture ofgrassy areas and scatteredshrubs and trees. Growth is

limited both by the region’s pre-cipitation and by the type ofsoil that is present. The hard

layers of the soil block thepenetration of roots. The

growth of the trees is alsocontrolled by the depth of

the water table, and the pro-ximity of surface water is

also important.

LEVELS OF TREE GRAZINGAlthough many animals survive byfeeding on the sea of grasses thatgrow on the savannah, other animals seek nourishment from thesavanna’s scattered trees. Differentspecies of animals eat from branches at different heights.Whereas the rhinoceros and dik-dikeat from the lowest branches, elephants and giraffes, thanks totheir higher reach, can eat from thehigher branches of the tree. Giraffescan consume leaves off branches as high as about 16 feet (5 meters)off the ground.

36 MAJOR BIOMES OF THE WORLD ECOLOGY 37

GIRAFFEGiraffa camelopardalis

AFRICAN ELEPHANTLoxodonta africana

MARABOULeptoptilos crumeniferus

AFRICAN WHITE-BACKED VULTUREGyps africanus

WHITE RHINOCEROSCeratotheriumsimum

LIONPanthera leo

WILDEBEESTConnochaetesTaurinus

TERMITEMOUNDS

BURCHELL’SZEBRAEquus burchelli