Temperature regulation of the polar bear (Thalarctos maritimus)

Abstract

• 1.

  1. The polar bear has developed thermoregulatory mechanism consistent with its semiaquatic way of life.

• 2.

  2. In vivo examinations of three adult polar bears were performed by radiotelemetry on bears in cages and by measurements on bear tied to a frame in air and in water.

• 3.

  3. Significant insulation is achieved by means of fur, blubber and other peripheral tissues both in air and water.

• 4.

  4. Vascular heat exchanges are present in the limbs, and two thin muscle sheets adjacent to the skin probably afford a special avenue of heat dissipation.

• 5.

  5. Insulation and heat dissipation seems, however, insufficient during extreme weather conditions, forcing the polar bear to utilize postural increase of insulation or to slow down activity during cold or warm weather respectively.