Top of page

Everyday Mysteries

« Back to Zoology page

Question Is a polar bear's fur transparent?


Yes!  Most sources indicate that the long, coarse guard hairs, which protect the plush thick undercoat, are hollow and transparent. The thinner hairs of the undercoat are not hollow, but they, like the guard hairs, are colorless.

Male polar bear near the Beaufort Sea,  Alaska,  2016.   Steven C. Amstrup,  USGS photographer, USGS Science Explorer .

The hair of a polar bear looks white because the air spaces in each hair scatter light of all colors. The color white becomes visible to our eyes when an object reflects back all of the visible wavelengths of light, rather than absorbing some of the wavelengths.

At one time it was suggested that the polar bear hairs might have some of the properties of optical fibers. Apparently this is not the case.

Polar bear with cub  (Ursus maritimus). Scott Schliebe,  USFWS photographer,  2010.  U.S. Fish & Wildlife Service National Digital Library.

Scientists in the late 1970’s discovered another interesting tidbit about polar bears. A number of polar bears in zoos from around the world were turning green! These scientists discovered that the algae responsible for making the bears green were not on the SURFACE of the hairs, as originally supposed, but were INSIDE the hairs (Lewin & Robinson, 1979). The algae more than likely came from the pond waters in the bears’ enclosures.

Two polar bears swimming in water in the Beaufort Sea,  2009.  USGS Science Explorer.

Published: 11/19/2019. Author: Science Reference Section, Library of Congress

Have a question? Ask a science librarian