Innovators are full of questions.Nature has answers.


  • Strategy

Fur provides insulation: polar bear


Polar bear spotted in Dierenrijk Europa Netherlands / Marieke IJs.. / LicenseCC-by - Attribution

Hair of polar bear insulates it from cold because it has low emissivity in infrared.

"Polar bears are masters at conserving energy. During their eight-month fast, breeding females can lose as much as 45 percent of their weight. So heat retention is important, to avoid spending too much energy to keep warm. The bears' fur is dense, made of clear hairs that scatter light, creating a white effect. Underneath the fur lies black skin that absorbs the sun's rays…polar bears are nearly invisible in the far infrared, the frequency range in which bodies radiate heat. Researchers from Berkeley's Department of Mechanical Engineering, led by professors Boris Rubinsky and Ralph Greif, found that the conventional explanation, that the bears are so well-insulated that their surfaces are the same temperature as the snow, is correct but incomplete: the hair's emissivity in the infrared is also nearly equal to that of snow and that this low emissivity could help to insulate the bears by lowering the amount of infrared heat that the bears radiate away." (Courtesy of the Biomimicry Guild)
About the inspiring organism
Polar bear
Ursus maritimus Phipps, 1774
Common name: Polar bear

Other Conservation Info: Listed as threatened under the U.S. Endangered Species Act
Habitat(s): Marine Neritic, Marine Oceanic, Shrubland
Learn more at
Some organism data provided by: ITIS: The Integrated Taxonomic Information System
Organism/taxonomy data provided by:
Species 2000 & ITIS Catalogue of Life: 2008 Annual Checklist

Threat Categories LONG_VU IUCN Red List Status: Vulnerable

Bioinspired products and application ideas

Application Ideas: Highly effective insulation for extremely cold conditions; camouflage clothing to avoid infrared detection; light and easily manipulated building material; more efficient solar water heaters.

Industrial Sector(s) interested in this strategy: Manufacturing

Department of Mechanical Engineering
Ralph Greif Boris Rubinsky
University of California Berkeley
Preciado JA; Rubinsky B; Otten D; Nelson B; Martin MC; Greif R. 2002. Radiative properties of polar bear hair. Proceedings of the ASME International Mechanical Engineering Congress and Exposition. BED-53: 1-2.
Learn More at Google Scholar Google Scholar  


Login to Post a Comment.
Is it the length and diameter of the hair that blocks infra-red or what?
1 to 1 of 1 Comments