From: BBC Earth
Published November 11, 2011 05:16 PM

Survival against all odds: Animals of the Arctic

Adaptation is fundamental for a species to survive, especially in hostile environments like the Arctic. When faced with six months of perpetual darkness where snow and ice lays claim to every inch of the land. What kind of extraordinary animals survive in such harsh terrain, and more importantly, how do they do it?

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During winter in the Arctic, temperatures can drop to a bone-chilling −50°C (−58 °F). Rather than going into hibernation however, some animals will stick out the winter and use their cold-conquering adaptations to survive. One such animal that has done this is the arctic fox or the snow fox as it is also commonly known.

Ranging far and wide in the arctic and alpine tundra, these jackals of the north, so-called because of their propensity to scavenge on polar bears' kills, have a woolly coat that has the best insulating properties of any mammal. Other adaptations for life in the arctic include small, heavily furred ears and a short nose. Having a smaller surface area reduces heat loss. They also have fur on the soles of their feet as well as increased blood circulation to the feet which literally stops their paws freezing to the ice!      

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 centimetres (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 defences serve as a pretty hardy armoury 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.

The adaptations that allow animals to live in such a hostile environment are incredible; join us again when we check out some even more incredible adaptations — those of the animals who inhabit the coldest place on earth, the Antarctic.

Photo credit:  BBC Earth

See more at: http://bbcearth.posterous.com/survival-against-all-odds-animals-of-the-arct

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