曹雪

Arctic animals need special protection against the freezing weather. Many have several layers of thick fur coats. The inner layer keeps them warm. The outer layer keeps them dry. Arctic animals also have extra layers of fat that trap in the heat. Moving around on snow or ice is difficult. Some animals， like the polar bear， have big feet. Their feet act like snowshoes and keep them from crashing through the snow.

Hibernation 冬 眠

Some Arctic animals escape the icy winter by curling up in their dens（兽窝;兽巢）. They drift into what seems like a deep sleep for most of the winter. But they are not actually sleeping; they are hibernation. All summer long， animals like the female polar bear and the Arctic hare eat as much food as they can. When winter arrives， they dig dens out of snow or leaves. Sometimes they find shelter in a cave. Then they curl up and become very still.

Hibernating saves the animals a lot of energy. Their heartbeat slows down. Their body temperature lowers. They breathe very slowly. The arctic ground squirrel’s body temperature is the lowest of all hibernating animals. It falls below freezing！ Sometimes hibernating animals leave their dens for a short time to find food. Then they head back to their warm dens and hibernate some more.

Migration 遷 徙

To escape the cold， many animals migrate in the fall. When animals migrate， they travel to distant places that are warmer. The animals return home in the spring when the temperature rises. Some animals travel really great distances. But no animal migrates as far as the Arctic tern. It flies more than 21，750 miles back and forth from the Arctic to Antarctica. That’s like flying between New York City and Los Angeles about eight times！ Some sea creatures migrate as well. Gray whales swim over 12，000 miles from the Arctic to the coast of sunny Mexico.

Changing Colors 变 色

To protect themselves from predators， some animals have fur that changes color during the year. In the summer， their fur is darker and blends into the grasses and shrubs（灌木丛）. In the winter， their fur is as white as snow. Animals like Arctic foxes， hares， and weasels are gray or brown in the summer. In the winter， they are completely white. This really confuses any predator （捕食者）that is looking for a tasty meal！