Polar bears skin is black and their fur is clear and transparent. So why then do polar bears look white
It is mainly because of reflection. While the hair is transparent it reflects the white light from the sun making the polar bears appear white in a similar way to snow and ice. Polar bear fur consists of a dense, insulating undercoat which is topped by guard hairs of various lengths. Each shaft of hair is pigment free and transparent and has a hollow core which reflects visible light. This is also reason why polar bears appear the brightest in direct sunlight. The more light there is the more of the light gets reflected by the transparent hollow polar bear fur.
Polar bears living in zoos have been known to sometimes turn green. This happens because algae grows in their hollow hair shafts which then reflects a different colour to our eyes. Making the polar bear appear green. This happens in warmer environments where algae naturally grows but doesn’t happen to the polar bears who live in the Arctic. In the Arctic it is too cold for the Algae to grow and so the polar bears stay appearing white. This helps the polar bears for hunting in the cold Arctic north.
Polar bear fur helps to keep them warm in a number of ways. The fur is oily which prevents water from being absorbed by the hairs. Because of this after getting out of the water the polar bear can shake themselves dry and all the water comes off. Polar bears are also kept warm by a thick layer of blubber which also helps to provide the polar bear with food during the long months where they are not hunting and going through a process known as walking hibernation.
You can read more about polar bears here
Also check out polar bear endangered