Some animals, such as bears, avoid the cold winter by sleeping right through it. An animal's body uses very little energy while asleep, thus negating the need to search for food in a harsh winter environment. Bears will gorge themselves on food during summer and fall, developing a thick layer of body fat. The fat not only provides nourishment to the bear while it hibernates, but also insulates the bear from the cold.
Animals on the arctic tundra are well known for their thick, shaggy coats. Fur provides excellent insulation, keeping the animal's body heat trapped close to their skin. Fur also provides camouflage, keeping prey hidden against the snow. Some animals, such as polar bears and caribou, have hollow hairs on their body, which is ideal for keeping warm. Humans have copied this design in creating insulation for jackets and winter coats.
Snow may be cold, but creating a shelter within it is actually an effective way to stay warm. Living underground allows animals to avoid harsh weather and cold winds. Many mammals living on the tundra have learned to burrow. This behavior is common in rodents, such as ermine, hares, and lemmings. Hibernating animals will also create burrows before lying down for their long winter's nap.
Tundra animals often have shorter limbs and extremities than their relatives in warmer climates. A more compact frame reduces heat loss. This is why, in contrast, animals living in hot deserts will have long limbs or big ears. The smaller the features, the warmer the animal remains.
By growing close to the ground and keeping their leaves small, tundra vegetation uses as little energy as possible to stay alive. Plants growing on the tundra also are extremely resistant to cold. Some species are even known to continue photosynthesizing from beneath the snow.
