Polar Bear Disguise
Polar bears actually have two different kinds of fur: the short and dense underfur that is against their skin, and the longer and more coarse guard hair.
This guard hair is transparent, and it scatters sunlight so that the polar bear looks white. However, the guard hair also absorbs the heat from a polar bear's body instead of transmitting that heat into the air. In this way, the bear is able to keep the heat in his body and stay warm in the cold Arctic air.
Because the polar bear's guard hairs keep his body heat in, he is invisible to a thermal camera. Thermal cameras detect the heat lost by a subject as infrared, but because a polar bear's guard hair keeps that heat in, a polar bear may not always be seen on this type of camera.
That's all for today. See you again on Friday!
