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Polar Husky A to Z

 

FROZEN FROGS

 

Yes. Frogs actually do live in the Arctic! One very developed frog -- the Wood frog -- has found its way to Alaska, Yukon and the Northwest Territories. Bear in mind frogs are amphibian, meaning they are unable to produce body heat, so the wood frog has evolved a rather astonishing method to survive the ferocious winters.

It freezes alive!

Two thirds of the water in its entire body is frozen solid most of the year. Hair from most Arctic, animals is not white, but clear, hollow and full of air making it easier for them to stay warm!

Pretty amazing stuff. Especially considering how cells burst and break causing frostbite once they freeze.. So how can it be possible for the frog to survive?

It is not the cells of the wood frogs that freezes, the ice forms in the spaces between the cells! The organs of the frog are surrounded by a mass of ice keeping them nice & cool without damaging them. This way the frogs "hibernate" without any body functions for which it would need energy. There is no heartbeat, it does not breathe and if you cut into it does not bleed! As the temperature gets warm in the late spring they recover life! How the freezing is "controlled" is still a mystery though.

This is what you call a highly developed arctic adaptation. Adaptation basically means "how an animal changes according to the environment it lives in". Biologists talk about two types of adaptations. One form of adaptation, called physiological adaptation, involves how one animal can change for example its behavior or habits because of sudden change in environment. The other kind of adaptation, discussed here, happens over many generations and is called evolutionary adaptation.

How does evolutionary adaptation work? To make a very long story short, evolutionary adaptations are the results of the competition among animals of the same breed or different breeds over many generations in response to an ever-changing environment. Certain traits -- certain things about the animal -- are culled by natural selection, favoring those animals that produce the most offspring. This is such a broad concept that, theoretically, all the features of any animal or plant could be considered adaptive. As the guy Charles Darwin - who was the first to put these thoughts on paper - says himself "..The leaves, trunk, and roots of a tree all arose by selection and help the individual tree in its competition for space, soil, and sunlight.."

So, how does this apply to Arctic animals? With the Arctic being such a frigid place to live, there is plenty of competition for food and other resources and the animals have to be highly adapted in order to survive. In other words, they need very specialized "gear" just like our team members.

Lets take a look at the two cousins - the red fox (Vulpes vulpes) and the arctic fox (Alopex lagopus). Generally the arctic fox lives on the tundra above the tree line whereas the red fox lives in the forests below the tree line. But lately the red fox, which is the most prevalent wild mammal on Earth, has tried to move in on his arctic cousins' territory.

The red fox can run faster, is more agile, bigger and heavier and commonly chases the arctic foxes away whenever they meet, but the little white fox still greatly outnumbers reds in the Arctic. It all has to do with energy. Overall, the red fox must use more energy and as such needs more food, because it is not as well adapted to arctic conditions. Everything about an arctic fox on the other hand fits perfectly for the arctic. Its feet are covered with fur, its coat is much better and compared to the red fox it has a much smaller muzzle and small ears reducing its exposed surface area, lessening the loss of body heat in the frigid cold!

Even before Darwin came around in the early 1800s a biologist named Joel Allen studied and developed a theory on how animals vary depending on the climate they live in -- whether it is warm or cold. This is also called a climatic adaptation.

Biologist Joel Allan developed a famous theory to explain how animals conserve heat. It goes like this: animals from cold climates have smaller ears, muzzles, legs and tails than their relatives from warmer climates. Does it sound familiar!

The arctic hare is another excellent example of the "Allen’ rule". An arctic hare living in Northern Greenland for instance has shorter ears, snout and legs than one living in Labrador about 3700 (6000 km) miles further south.

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