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Animal profile
Ursus maritimus
The polar bear is the largest living bear, a marine mammal that hunts seals from the surface of Arctic sea ice. It diverged from brown bears within roughly the last half-million years and retains the ability to hybridise with them. Its dependence on sea ice for hunting makes it unusually sensitive to changes in ice extent and season length.
Each guard hair is a hollow, colourless tube. It looks white because it scatters light, over black skin. The popular claim that the hairs pipe sunlight down to the skin like optical fibres was tested and found to be wrong.
Each guard hair is unpigmented and hollow-cored, and the skin beneath is black. The animal looks white because the hairs scatter light in every direction, not because any pigment in the coat is white.