Homeostasis
Polar bears (Ursus maritimus) and other mammals living in ice-covered regions maintain their body temperature by generating heat and reducing heat loss through thick fur and a dense layer of fat under their skin.
Source
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"OpenStax College, Themes and Concepts of Biology. October 16, 2013."
http://cnx.org/content/m44388/latest/Figure_01_02_12.jpg
OpenStax CNX
CC BY 3.0.
