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No. 45: May-Jun 1986

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Polar Bear Coats Are Thermal Diodes

"A polar bear's hairs are completely transparent. The bear appears white because visible light reflects from the rough inner surface of each hollow hair. However, the hairs are designed to trap ultraviolet light. Like light within an optical fiber, the radiation is conducted along the hairs to the skin. This summertime energy supplement provides up to a quarter of the bear's needs. Thus, even while actively pursuing prey, the bear can still concentrate on building up its blubber layers in preparation for winter."

In other words, the bear's fur lets heat in but not out -- in effect a thermal diode.

(Anonymous; "Solar Bear Technology," Science News, 129:153, 1986.)

Comment. How come polar bears are favored with this "marvelous adaptation" while the arctic foxes and other mammals shiver?

From Science Frontiers #45, MAY-JUN 1986. © 1986-2000 William R. Corliss

Science Frontiers Sourcebook Project Reviewed in:

Quotes

  • "Before opening the book, I set certain standards that a volume which treads into dangerous grounds grounds like this must meet. The author scrupulously met, or even exceeded those standards. Each phenomenon is exhaustively documented, with references to scientific journals [..] and extensive quotations" -- "Book Review: The moon and planets: a catalog of astronomical anomalies", The Sourcebook Project, 1985., Corliss, W. R., Journal of the Royal Astronomical Society of Canada>, Vol. 81, no. 1 (1987), p. 24., 02/1987