Why do polar bears have to be white?

Answer 1

Well, they don't HAVE to look white, but it does help them sneak up on their prey better in the great white north and to be more hidden in their snowy dens with their young, to keep them from predators.

Their fur is actually not even white, it is more the color of our fingernails, sort of the yellowish milky transparent color of keratin which is what hair and finger nails are made of. Their fur just doesn't have additional color pigments added to the natural color of the keratin. It looks white because of its reflective abilities in the light. There are long guard hairs and a shorter undercoat, the longer hairs are hollow. This allows them to hold air that insulates the bear from cold. It also allows some sun to make it to their skin so it can absorb the heat, their skin is black and absorbs the light rays, but, so they don't overheat now that they are adapted to the extreme cold of the Arctic, the hair also can reflect a large amount of the light on long sunny days to keep them from getting too hot with the black skin.

Besides, everyone likes something that looks soft, warm, fuzzy and pure white!