Physiology

Teeth.
A polar bears mouth is very well adapted to a carnivorous lifestyle and just like other predators, they have the teeth to match. The most predominate part of the bears mouth is the large canines, which are used to grip the prey which makes it difficult for the prey to become free. The canines become fully formed at 3 to 4 years old (Larson, 1971). The incisors at the front of the mouth as used to tear prey apart and although they have molars, these are not frequently used. Teeth can become damaged and broken after fighting or during a hunt, and this can hinder the bears success at catching and consuming prey. If the teeth and jaw are badly damaged and so they cannot eat, this will lead to starvation and death for the bear.

Fur

The coat of a polar bear is one of the most important adaptations as without this they would get freeze very quickly. The hairs are transparent and are made of a hollow tube which reflects light and makes it appear white. It is made up of two layers, the first a short dense layer of underfur, which traps air close to the skin and provides more insulation. The second layer is made up of longer guard hairs (5-15cm) which help to stop wind and water from getting through to the skin. Moulting begins in spring and finishes in late summer, and this is when polar bears are whitest. The yellow appearance of the fur is due to a build up of seal oil within the hairs and the colour is strongest before malting. The skin of a polar bear is actually black, and this is to absorb and retains as much heat as possible from the sun. A layer of blubber about 10cm thick lies just under the skins surface and this not only provides insulation, but also a source of energy when food is scarce. Its small ears and tail reduce the surface area and therefore reducing heat loss.

Paws
Huge paws allow the polar bear to walk across very thin ice by distributing weight across a larger area. They also walk with their legs wider apart when on thin ice to help minimize the chance of falling through. Although it looks very amusing in this clip, this behavior will become more frequent in the coming years as the ice thins.

Paws can reach up to 12 inches across with non-retractable claws up to 2 inches long. The claws are not only used for tearing into prey, but also for traction when running and climbing, digging into surfaces and gripping onto rocks. In addition to these adaptations, they also have papillae, which are dermal bumps on the pad of the foot, which help prevent slipping on ice.

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