The skin beneath a polar bear’s white fur is black.
Polar bears live across the Arctic and are adapted to cold, seasonal darkness, and icy water. Their black skin absorbs solar radiation more effectively than pale skin would, although the thick layer of fur and body fat provides most of their insulation. The fur itself is not truly white in a pigment sense: individual hairs are largely colourless and can scatter light, making the coat appear white or cream.
A polar bear’s coat can look yellowish, especially when stained by oils, dirt, or algae. It may also appear greenish in captivity when algae grow inside the hollow hairs under particular lighting conditions. These visual changes do not mean the animal has changed its natural fur colour.
The black skin is easiest to see around the nose and lips. Polar bears also have compact ears and a short tail, features that reduce heat loss compared with many terrestrial mammals.