Polar bear fur is made up of a dense, insulating underfur that is topped by guard hairs that vary in length. The fur prevents almost all heat loss—in fact, adult males can quickly overheat when they run.
And surprisingly, the fur isn’t actually white—it just looks that way. Each hair shaft is pigment-free and transparent with a hollow core that scatters and reflects visible light, much like what happens with ice and snow.
Polar bears look whitest when they are clean and in high-angle sunlight, especially just after the molt period, which usually begins in spring and is complete by late summer. Before molting, accumulated oils in their fur from the seals they eat can make them look yellow.
Skin, Ears, & Tail: Staying Warm
To keep them warm, polar bears have black skin over a thick layer of fat that can measure up to 11.4 centimeters (4.49 inches).
In the water, they rely more on their fat layer to keep warm; wet fur is a poor insulator. This is why mother bears are reluctant to swim with young cubs in the spring—the cubs just don't have enough fat.
Their skin isn’t the only thing working to keep them warm—their ears are small and round, and their tails short and compact, to conserve the most heat possible.
Paws & Claws
Polar bear paws are ideal for roaming the Arctic.
They measure up to 30 centimeters (11.81 inches) across, to help polar bears tread on thin ice. When the ice is very thin, the bears extend their legs far apart and lower their bodies to distribute their weight.
Polar bear paws aren’t designed to help just on land. When swimming, the bear's forepaws act like large paddles and its hind paws serve as rudders.
Black footpads on the bottom of each paw are covered by small, soft bumps known as papillae. Papillae grip the ice and keep the bear from slipping. Tufts of fur between its toes and footpads can help with security as well.
As can their claws. Thick, curved, sharp, and strong—each measures more than five centimeters (1.97 inches) long. Polar bears use their claws to catch and hold prey and to gain traction on ice.
Watch polar bears as they travel across the sea ice to hunt seals.
Polar Bear FAQ
We answer the most frequently asked polar bear questions.