Animals living on the tundra have characteristics suited for extreme cold, such as heavy fur coats and small ears. Many also have behavioral adaptations, such as traveling south for winter or huddling together for warmth.
The tundra is characterized by permafrost, which means that only a relatively shallow layer of soil thaws during the summer. Below that, the soil is permanently frozen. The extreme temperatures and long winters that cause this mean that animals must be well-suited for cold. Many tundra animals have white or light brown coats to help them blend into the winter landscape. Tundra mammals have thick coats, and many have a double coat. This means they have both a thick fluffy undercoat to trap warm air near the body and long slick outer hairs that help water and snow slide off the body.
Tundra animals also expose as little skin as possible. Mammals typically expose the most skin around their muzzles and ears and sometimes around their paws. Tundra animals tend to have small ears, short legs and short snouts to help minimize heat loss. Some tundra animals, such as polar bears, have a thick layer of blubber to help insulate them from the cold.
Behavioral adaptations are also important characteristics of tundra animals. Arctic hares and musk oxen are famous for huddling together in large groups to help share body heat. Others, like brown bears and ground squirrels, hibernate during the long winters.