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НазваThe animals of Americas (реферат)
РозділІноземна мова, реферати англійською, німецькою
ФорматWord Doc
Тип документуРеферат
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North and South America comprise the only continuous land mass that

reaches from the north to south polar regions, a distance of more than

14,500 km (9,000 mi). The combined area of the two continents is 41.4

million sq km (16 million sq mi), in which are found all terrestrial



The two continents have been joined for the past two or three million

years. Earlier South America was an island, set apart from the northern

land mass for at least 60 million years. This gave time for animal

species unique to the continent to evolve. After the Isthmus of Panama

emerged, there was an interchange of animals between North and South

America, much as that experienced by Eurasia and America during the Ice

Ages. One of the animals found in both Eurasia and America is the polar

bear. Its habitat is along the entire Arctic coast. It has even been

sighted hunting seals on ice floes hundreds of miles at sea. The polar

bear's heavy coat insulates it from the icy water and air. Thick hair

growing between its toes keep it from slipping on the ice. The thick,

white pelt made the animal a prized trophy and reduced its population.

The bear is now protected throughout its range.


The musk ox, resident of the far north, also has had to be protected

from excessive hunting. At one time it came very close to extinction. A

member of the cow family, the musk ox has adapted to the bitter cold by

developing a heavy, shaggy coat consisting of two parts — a coarse outer

covering of long guard hairs and a soft inner coat so dense that neither

cold nor moisture can penetrate.


Musk oxen form a defensive ring when threatened. Adults stand along the

perimeter, heads and horns pointing out, and the calves cluster together

inside. This defensive posture works well against the ox's chief enemy,

wolves, but is of little avail when high-powered rifles are the enemy.


Wolves prey on many species in the north — musk ox, caribou, moose,

deer, hares, and even rodents. These carnivores are among the most

maligned of all animals, victims of false myths and legends and

systematic programs of extermination. They are accused of attacking

humans and destroying entire herds of domestic animals. But their

depredations of livestock are less severe than often claimed. And

unprovoked attacks by healthy wolves in North America on humans are

unknown. Those recorded from Europe's Middle Ages are thought to have

been made by rabid animals or hybrids.


The world will be a far lonelier place if the last wolf dies. As

biologist Ernest P. Walker wrote in his book, Mammals of the World, "The

howl of the wolf and coyote, which to some people is of more enduring

significance than superhighways and skyscrapers, should always remain a

part of our heritage."


Some Arctic wolves remain snow white year round, an adoption to their

environment. Three other predators of the far north— the snowy owl,

Arctic fox, and weasel— are white at least part of the year.


The life cycle of the snowy owl demonstrates the close relationship

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