Another such master of retaining body heat is the walrus.
Walrus are covered with short coarse hair that becomes less dense as they get older. Their skin which is folded and wrinkled can be up to 4 cm thick serving as a great insulator. This tough skin is the thickest on the neck and shoulders of adult males where it also serves as a defensive purpose – when these bulls spar, the thick skin is intended to resist tusk penetration.
They have a deposit of fatty tissue that is up to an astounding 15 centimeters (6 inches) thick – in winter it may make up to a third of their body mass. As well as being an excellent insulator, it also streamlines the body and is used as an energy reserve.
Their outer defenses serve as a pretty hardy armor but even this thickest of ‘winter coats’ is not sufficient when diving to depths of over 180 meters for nearly half an hour at a time, so the walrus has another trick up its sleeve. When they enter the cold arctic water they become paler because they have a mechanism that restricts blood flow to the skin in order to reduce heat loss. Conversely, when walruses are warm their skin is flushed with blood and they appear to be very red.
This post was originally published by BBCEarth.
Photo from Brandon Christopher Warren via flickr
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