Why don't polar bears freeze in the icy Arctic waters?

In a polar bear’s Arctic home, winter temperatures can drop as low as -50 degrees Fahrenheit (-45 degrees Celsius). A polar bear spends the winter living on sea ice, but the bear is so well insulated that it doesn’t freeze in these extreme temperatures. A layer of fat more than four inches thick, a thick fur coat, and special white hairs that absorb the heat of the Sun keep the polar bear warm. During ice storms—when wind and blowing snow make travel and hunting too difficult—the polar bear curls up and lets the snow cover it completely. Although this stunt sounds chilling, it is warmer under the snow than aboveground, where the animal is exposed to the freezing air.