The Polar Bear Essay Research Paper INTRODUCTIONUrsus

The Polar Bear Essay, Research Paper

INTRODUCTION

Ursus maritimus, commonly known as the polar bear, is quite an amazing animal. The polar bear is of the order Carnivora and of the family Ursidae. Polar bears live in the extremely cold regions of the Arctic and in Tundra. They range from Alaska to Siberia, and have been found as far as 720 miles south of the Arctic Circle. The polar bear is quite huge. They can be as tall as 8.25 feet when on all four feet, or 12 feet when standing on their hind legs and weighs up to 1,764 pounds. The polar bear is carnivorous and can be very ferocious when necessary, but is about the most gentle bear of all. Living in such a harsh climate and being strictly a meat-eater has molded the polar bear into an incredible mammal with many special features.

MOVEMENT

Since polar bears are carnivores and there isn t a lot of food in the Arctic, they must be able to travel a great distance at a good speed. Looking at a polar bear you will probably notice that it is bowlegged. This means that their huge paws point inward. Having their paws in this position helps them grip the slippery ice. Another specialized feature of its paws is that they have pads of dense fur on the bottoms. Polar bears are the only bears that have this feature. These pads help the bear retain heat and to grip the ice and provide better traction. Polar bears are fast movers. When on uneven ice the bear will trot , moving its legs on opposite sides in unison. It can trot at 12 to 18 miles per hour. When it is running, it can reach speeds of up to 35 miles per hour. The bear can travel around 50 miles on an average day.

The polar bear is also an expert swimmer. The bear has a long neck with a small head which help it to be more streamlined when it is in the water. It also has partially webbed feet which help it to paddle through the frozen waters. When swimming, the polar bear propels itself with its front paws and steers with its hind paws. While it is in the water the polar bear keeps its eyes open, its ears flattened to the side of its head, and its nostrils shut off. When the bear is in water it can swim at around 3 to 6 miles per hour and can travel up to 100 miles nonstop as long as it surfaces for air every couple of minutes.

FEEDING

Polar bears need large amounts of food. Fully grown polar bears can hold up to 200 pounds of food in their stomach. Polar bears eat a wide range of food. They will eat fish, walruses, dead sea animals that get washed ashore, seals, and it has even been reported that the polar bear has killed the beluga (white whale) from time to time. It has also been reported that polar bears have killed humans, but this was not for food, just self defense. The polar bear s favorite food is the ringed seal.

To get this food, the polar bear obviously must be a great hunter. Since polar bears largest percent of eating is of the seal, it would be most important to discuss how the bear hunts for seal. Polar bears are intelligent hunters and know where the seals are just by looking at the areas of ice. A polar bear can even smell a baby seal through 6 feet of snow and can pick up the scent of seal breath from a great distance. Normally, the polar bear has two types of hunting areas, above ground and underwater. Above ground, it will look for a seals breathing hole in the ice. Once it finds the hole it will just wait like a statue until the seal comes to get air. When the seal comes for air, the polar bear grabs the seal by its neck. Then it yanks it through the ice. Normally this will break most of the bones in the seals body. When the polar bear is going to hunt underwater, it will lower itself in without even making the water ripple. Then it glides through the water slowly advancing on its prey until the final lethal rush. Sometimes when a polar bear is on the edge of the water waiting to jump in and attack its prey, it will hold its nose so the seals will not see its familiar black nose.

Once the polar bear has caught its seal, it will usually eat just the skin and blubber. The bear will eat very quickly, eating large chunks and not even chewing for about half an hour. It does this so no other animals will come and steal the food from it while it is eating. After it is done, the bear will climb in the water and wash its face and paws. It may do this for up to 15 minutes.

Polar bears, like any other animal, need a good supply of fresh water in their diet. Since there is mostly ocean in the Arctic, the polar bear has to get its water elsewhere. It looks for old ice. It knows that in these areas of old ice, the salt has settled down through the ice blocks and left behind puddles of fresh water.

RESPONSE

Living in such harsh climates as the Arctic, a polar bear has to have great senses and other adaptations in order to survive. It has one of the best senses of smell of all animals. It can smell a kill from several miles off and as previously noted, seal breath from a great distance. They first pick up a scent in the driving air, then follow it like a single beam back to its source. The beam is probably rather narrow, and to keep it in focus, the great bears occasionally stand upright and sniff, moving their head from side to side. It also has excellent vision. It can tell what is going on around it just by a quick glance and often will see its prey long before its prey sees it.

The polar bear also has extremely thick fur. The fur is hollow, providing insulation. This is what makes the polar bear waterproof. If they were not waterproof, they would just turn into a block of ice when they jumped into the frigid water to catch their prey. It also keeps them nice and warm in the winter. In the summer, however, they get extremely hot. To cool down, they roll over on to their sides and stick their paws out. This activity sends the heat out through their pads, lowering their body temperature.

Below all the fur, there is a 4 to 5 inch thick layer of fat (blubber). This blubber also serves to keep the bears warm. Occasionally, however, it gets too cold and the bear has to resort to other means of keeping warm. The bear will actually plow itself into a snowdrift and stick its rear end up to block the wind while its front end is under the snow.

On the other hand when it gets too hot to stand, the polar bear will dig itself a cave into the permafrost. The bear will keep coming back to the cave year after year. Eventually the cave can become quite deep.

REPRODUCTION

With polar bears, mating usually takes place in April and May on the sea ice. When the female is in heat, she will start marking her trail with several urination s a day. The male polar bears can tell instantly the tracks of a female in heat. The male will follow the tracks for several days until he finds her.

When the male meets the female, there is usually another male that he must fight with for the right to mate. The winner then goes off with the female and they walk together for a couple weeks. The male polar bear will test the female constantly to see if she is ready. When she is, the two will mate several times over about a week.

After the female is pregnant she must gain a couple hundred pounds of fat to have a successful pregnancy. Also, she will build a maternity den where she is to have her cubs.

After she builds her den, it takes about one to two months before she gives birth. When cubs are born, they are very tiny and only weight around 1 pound. The cubs eyes stay closed for about 30 days and their canine teeth only become apparent after about 50 days. The cubs begin to walk after about 2 months. The mother nurses the cubs for a couple more months. The cubs will stay with their mother for a couple years before they leave.

Most polar bears don t reproduce until they are around the age of five. The female will probably lose her first litter. Most litters are usually twins, however, some may be as large as four.

CONCLUSION

By now you can see what amazing animals polar bears really are. Today, polar bears are endangered animals and may become extinct if poachers aren t stopped. However, an agreement between several countries was recently signed saying that people can t hunt them. This may help to protect them to some degree, but in the long run they will probably be killed off, except those maintained in zoos.