why do polar bears have short legs

Polar bear paws are idealPfor roaming the Arctic. They measure up to 30 centimeters (11. 81 inches) across, to help polar bearsPtread on thin ice. When the ice is very thin, thePbears extend their legs far apart and lower their bodies to distribute their weight. Polar bearPpaws arent designed to help just on land. When swimming, the bear'sPforepaws act like large paddles and its hind paws serve as rudders. Black footpads on the bottom of each paw are covered by small, soft bumps known as
papillae. Papillae grip the ice and keep the bear from slipping.

Tufts of fur between itsPtoes and footpads canPhelp with security as well. As can their claws. Thick, curved, sharp, and strongeach measures more than five centimeters (1. 97 inches) long. Polar bearsPuse their claws to catch and hold prey and to gainPtraction on ice. It is a natural reaction when cold to curl up into a tight ball to keep warm. Not only does this trap warm air, but it lowers the surface area, or amount of skin exposed, from which heat can be lost. Small animals have larger amounts of exposed skin compared to their overall volume.

In other words they have a larger surface-to-volume ratio, which means there is more area from which heat is lost relative to their total size. The opposite is true for larger animals. Many arctic mammals exploit this mechanism to reduce heat loss; they are larger than their temperate or tropical relatives. For example, the polar bear is huge compared to the sun bear a tropical relative. The ultimate heat conserving shape would be a sphere, but polar bears shaped like beach balls would have trouble getting around the tundra!

Bigger, however, is not always better in the Arctic, especially for appendages. Many arctic animals have small appendages. The best example of this pattern is the arctic fox, which has reduced external appendages including muzzle, ears, legs, and tail, compared to its temperate zone relatives. Reduced appendages decrease the arctic fox's surface-to-volume ratio, and thereby reduce the amount of exposed surface from which it loses heat. Long ears may be all the better to hear with, but they are also far more likely to get frostbitten!

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