Polar Bears Have Black Skin

A polar bear's brilliant white coat is one of nature's most effective deceptions. The fur isn't actually white; each hair is a transparent, hollow tube. This structure scatters and reflects all wavelengths of visible light, much like a pile of snow or salt, which overwhelms our eyes and creates the appearance of a pure white coat. This optical trick provides the perfect camouflage for hunting on the Arctic ice, allowing the bear (Review) to blend in seamlessly with its snowy surroundings.

Beneath this impressive illusion lies an even more surprising adaptation: jet-black skin. The dark skin serves as a passive solar collector, absorbing the sun's warming rays that penetrate the translucent fur. The hollow hairs not only provide excellent insulation by trapping a layer of air, but they may also help to channel solar radiation down to the skin's surface. This clever combination of a heat-absorbing base layer and a transparent, insulating overcoat is a crucial part of the polar bear's strategy for surviving in one of the coldest environments on Earth.