South of the taiga, Eurasian biomes become less clearly defined. Much of the area is flat and treeless. In the west, where rainfall is adequate, grass grows thickly. But deep in the continent's interior, the land becomes a desert. Here, thousands of miles from the moderating effects of the ocean, temperatures can climb well above 38°C (100°F) in summer, and plummet far below freezing in winter.
Animals must make drastic adjustments to these climatic extremes. One of the most common is migration. Herders move their domestic herds and flocks, following the seasons, and many of the wild grazers also make similar journeys, with predators following along.
The animals which are permanent residents have adapted to the heat, cold and aridity of this area. The saiga, an antelope-like animal, has nostrils pointing downward to help keep out dust. Inside each of its nostrils the saiga has a sac which is believed to warm and moisten the air.
The Bactrian camel of Mongolia and China has adapted to its environment by growing a thick, shaggy, winter coat; broad, split hooves to keep from sinking into the sand; and two humps for storing fat when foraging is poor.
Several species of wild asses are native to the interior of central Asia. Among these are the Mongolian kulan and Iranian onager. Asses are smaller than true horses and characterized by long ears, deep-set eyes coarse, wiry manes, small feet and tails tipped with long hairs. They can survive longer without water than other members of the horse family and are able to get along on a small amount of food. Because of their sure-footedness and endurance they are valuable beasts of burden and have been domesticated for centuries.
The Eurasian grassland is home to the heaviest of all flying birds, the 20 kg (45 lb) great bustard. And the world's smallest crane, the demoiselle which stands just 1 m (39 in) tall, breeds on grasslands from southeastern Europe into central Asia.
Several species of wild sheep and goats live on the grasslands and adjacent mountains. Markhors and turs, both goats, range from Spain to India and northward into Mongolia and Siberia. The tahr, a goatlike animal, is found in the high Himalayas. Goats differ from sheep in that they have beards, feet with scent glands, convex foreheads, and a definite odor among the males.
Some of the world's most unusual mammals live in the mountains which separate central Asia from India. One of the best known is the giant panda, once considered a member of the raccoon family and now thought to be related to bears. This animal lives on a diet consisting mainly of bamboo shoots. For unknown reasons the bamboo is dying, which threatens the pandas' future. The Chinese government has commissioned a team of biologists to study the situation. Although giant pandas have rarely reproduced in western zoos, a number of babies have been born in the Beijing zoo through natural conception, and artificial insemination has recently been successful.
The giant panda shares its bamboo forest with the lesser panda. This animal looks like a raccoon but is related to the giant panda.
Central Asia is isolated from India and Burma by the Himalaya mountain range, the highest mountains on earth. The area is so remote that little is known about the behavior of many of its animals. It is the home of a collie-sized gazelle, several species of wild sheep, and a member of the cow family, the yak. The yak is also domesticated and has been a beast of burden and supplier of milk, wool and fuel for many centuries.
One of the most beautiful of all Himalayan animals is the snow leopard, or ounce. Its fur is in great demand and poaching has placed it in grave danger of extinction.
The snow leopard's main prey is the bharal, or blue sheep, which lives in the Himalayas and other high mountains in eastern Asia.
As one moves south from the high country, the character of the land and its animals change. Rugged mountains give way to forested foothills. This country is the northern edge of the sloth bear's range which also includes other parts of India and Sri Lanka (Ceylon). Termites are a part of the sloth bear's diet, and it sucks them in by a "vacuuming" process. The bear rips open the termites' nest with its claws, then blows away the dirt and dust, and starts sucking. Its lips protrude; its nostrils close to keep out dirt.
Реферат опубликован: 21/12/2008