Make up of the Polar Bear
Weight and Size:
Did you know that polar bears are the largest land carnivore on earth? How big are these massive creatures?
Males polar bears:
Largest Polar Bear ever Recorded:
Weight: 12, 209 pounds
There are also features of the polar bear which deal with the structure of the polar bear. The polar bear body is more elongated than those of other bears, and the well-developed hind portion of the body is more prominent. The shoulders are very deep, further accentuating the hind portion. The neck is long and rather thin. The head of a polar bear is oblong and relatively small compared to its body size. The muzzle is elongated with a slightly arched snout. The nose is broad and black, and a polar bear’s eyes are dark brown which are set relatively close together, and point directly forward. The only bristles located on the bear are above the eyes and on the upper lip. A feature that many people may not know is that polar bears do not have eyelashes. The ears are small and rounded and lay flat while the bear is under water. The tail is also small, being approximately 2.8 to 4.7 inches long. The polar bear is also very careful when hunting and also has a special feature with its nose. When a polar bear is stalking its prey, it is a theory that they will cover their nose with their paws and when polar bears swim under water, they are capable of closing their nostrils.
The limbs on a polar bear are rather large and stocky. The hind limbs are longer than the forelimbs. The hind limbs are longer so that the large, muscular hind end is able to stand higher than the shoulders. The feet of a polar bear are long, wide, and thick. The forefeet are broad and round and the hind paws are elongated and less broad than the forefeet. Each of the toes, which are thick, curved, and has non-retractable claws, and is very massive. The claws are used for grasping prey, for traction when running, or climbing on ice. Up to half the length of the toes is covered with a swimming membrane. The sole of a polar bear’s foot has thick, black pads covered with small soft papillae (dermal bumps). The papillae create friction between the foot and ice to prevent slippage. Also, long hairs grow between the toes to help prevent slippage on the ice.
Polar bears are obviously not well adapted for swimming. However, they do possess a number of characteristics that help them in the water. While swimming, the polar bears use only the front paws to paddle, while the hind paws extend rigidly behind the act as a rudder. When making a sudden turn, the bear rears up by paddling all four legs. Polar bear’s great strength and stamina are of great help in propelling them through the water. More characteristics about the polar bears has that helped them with swimming are having a thick covering of blubber which insulates the bears in the water, just as it does in the outside air. Their oily skin and hair also help the polar bear to swim in the icy waters. The oily skin and hair keeps the icy water from preventing the bear and also acts as a waterproofing method.
Since polar bears are carnivores, their teeth are an important feature. Polar bears have 42 teeth, which are used for capturing their food and also for aggressive behavior. Postcarnassial teeth are greatly enlarged and the occlusal surfaces are “wrinkled” and adapted for crushing. Both the upper and lower carnassial teeth have no shearing function. The first three premolars are usually simple or may be lost. Polar bears use their incisors to shear off pieces of blubber and flesh, while canine teeth grasp prey and tear through hides. Polar bears are not the type to chew their food thoroughly. Polar bears swallow most food in large chunks rather than chewing.
Polar bears exhibit “carnivorean lethargy”. This sleep behavior can be characterized as a deep sleep which enables them to escape periods of poor hunting and extreme weather conditions. Once the bear has entered this deep sleep, various body functions slow down or are completely stopped. Metabolism in a resting bear is much slower than usual. The body temperature drops one or two degrees from normal. With minimal activity, the oxygen demand is much lower than usual and the breathing rate is slowed down. Since no food is being consumed, the digestive organs and kidneys cease functioning almost completely. Polar bears have a simple intestinal track, of which the colon is the primary site of fermentation. They have a long gut for digesting grass, but do not digest starches well. Their small intestine is longer than that of the true carnivores, and the digestive track lacks the features of the true herbivores. The barrel-shaped body of the bear is considered and indications of a long intestine.
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|Page last updated March 17, 2005|