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Polar bears' fur consists of a dense, insulating undercoat topped by guard hairs of various lengths. It is not actually white—it just looks that way.
Each hair shaft is pigment-free and transparent with a hollow core that scatters and reflects visible light, much like what happens with ice and snow.
Polar bears have black skin under which there is a layer of fat that can measure 4.5 inches (11.5 centimetres) thick.
Scientists used to think that polar bears' hollow hairs acted like fiber optic tubes and conducted light to their black skin. In 1988, Daniel W. Koon, a physicist at St. Lawrence University in Canton, New York, and graduate assistant, Reid Hutchins, proved this false.
Their experiments showed that a one-fifth inch strand of polar bear hair conducted less than a thousandth of a percent of applied ultraviolet light. So, the black skin absorbs very little ultraviolet light. Instead, Koon believes keratin, a basic component of the hair, absorbs the ultraviolet light.
Thank you to Dr Koon for this information.
- 1 Reply to Roy
"I think i made it clear i am bored with these shinanigans!!"
No, you made it clear it was over when YOU say it's over.
" I notice you had nothing to say about Polar Bears "
I have no interest in polar bears, now, if you want to discuss orang-utans ....