Adaptations of the polar bear to cold environments

Large size

Polar bears are the world's largest land-based carnivore, almost 700 kg. This helps them retain their body heat because large animals have a higher volume to surface-area ratio, so they lose less heat through their skin.

Small ears and tail

Appendages that stick out also affect the volume to surface-area ratio and cause more heat loss as discussed above. The polar bear's small ears and tail offer less surface area than large ears or tails, and help maintain body warmth.

Fat

Polar bears have a layer of fat that can be four inches (10 cm) thick. Although their fur is the primary source of insulation, the fat helps keep heat in as well. The milk of polar bears is extremely high in fat and protein, the fatty milk helps small cubs, who are more vulnerable to the cold, put on critically important body weight quickly.

Thick fur

Except for the tip of the nose, polar bears are entirely covered in fur. They have a very thick undercoat, which is even denser than the coats of other bears, as well as longer guard hairs. This insulates them from the cold, even when they are in water. Their fur is also hollow and transparent. Their fur has another use as well: the hairs reflect light, making polar bears look white and helping them camouflage among the snow and ice.

Water repellent fur

Polar bear fur sheds water like a Gore-Tex jacket, so even after a swim, they don't stay wet long. oils in the hair help with this. Water has a very high heat capacity, which causes it to channel heat out of the bear's body, so the faster they dry, the faster they stop losing heat.

Large Anti-Slip Paws

Polar bears have enormous paws! On land, they are like snowshoes, spreading the bear's weight and helping them move across soft snow and thin ice. On ice, they keep the bear from slipping: they have footpads covered by papillae (small soft bumps) and claws that are short, thick, and curved. The paws also are covered in fur for both traction and warmth.