The polar bear’s fur and blubber help keep it warm.
Polar bears are found in very cold parts of the world where temperatures can drop as low as -20° Fahrenheit (-29° Celsius). Without proper protection, this weather can be deadly, so polar bears keep warm using their thick fur and blubber or blubber. Polar bears have evolved along with other Arctic animals to take advantage of minimal heat and can sometimes get very hot because their bodies are very efficient at retaining heat.
A polar bear’s fur is the first step in keeping warm. In fact, polar bears have two types of fur: long, oily fur and short, insulating fur. Polar bears keep warm by combining the properties of these two hairs. The protective wires are actually hollow and look like very small glass tubes. Hollow guard hairs trap heat and bring it close to the skin, while providing an oily outer layer that prevents the polar bear from getting wet. Insulating fur holds heat close to the skin, much like human insulating underwear.
Fat also helps polar bears keep warm by providing an insulating pad of fat on certain parts of the body. While polar bears don’t use fat as efficiently as some Arctic animals, it certainly adds a layer of protection and can also be used as an energy source when food sources are minimal. The fat is unevenly distributed over the bear’s body and ranges from 2 to 4 inches (5 to 10 cm) thick. Fat also combines with protective threads that trap air to keep polar bears afloat in the water.
Scientists have also seen polar bears warm themselves using snow. Snow crystals trap small amounts of air, and polar bears dig burrows in the snow to create an insulating blanket that, while cold, is warmer than the outside world. This is sometimes combined with a biological process called winter sleep, which slows down metabolic processes. Winter sleep isn’t exactly hibernation, as bears can be woken up, but it does create a lower energy demand on the body, which will keep them warmer.
Using this variety of physical and physiological adaptations, polar bears stay warm even in the coldest winters. In summer, polar bears shed some of their winter fur and blubber, but they can overheat in extremely hot weather. Polar bears stay cool in the heat, spreading out to increase their surface area and diving into Arctic waters, which are still cold even in summer.