Реферат на тему Polar Vs Brown Bear Essay Research Paper
Работа добавлена на сайт bukvasha.net: 2015-06-13Поможем написать учебную работу
Если у вас возникли сложности с курсовой, контрольной, дипломной, рефератом, отчетом по практике, научно-исследовательской и любой другой работой - мы готовы помочь.
Polar Vs. Brown Bear Essay, Research Paper
There are eight different species of bears found throughout
the world: the spectacled bear, the Asiatic black bear, the brown
bear (including grizzlies), the polar bear, the sun bear, the
American black bear, the sloth bear and the giant panda.
Even though most people can distinguish a polar bear from a brown
bear by the color of the fur, a lot of people fail to identify all the
differences among those two species. Both bears can be perceived as
large, clumsy and lumbering beasts with heavily built bodies but short
legs, necks and tails. Both of them have rounded ears and noticeably
small eyes relative to their large body size. While both of the bears
belong to same family, they have several profound differences. They
live in different geographical areas, differ in amount of the
population, size, physical features, some eating habits, and their
behavior toward human beings.
The polar bear is found in all of the polar regions of the entire
northern hemisphere. This includes Russia, Norway, Greenland, The
United States and Canada. Their preferred habitat is in the area where
the northern seas meet the shoreline. In this area, there is a constant
freezing and thawing of the ice. It is estimated that there are
currently somewhere between 20,000 and 40,000 polar bears.
The polar bear is the largest member of the bear family, weighing
in at between 440 and 1760 pounds with overall body length 11.5 feet.
It can grow much larger, however. In fact, there is a record of an
adult polar bear weighing over 2200 pounds.
Polar bears have a distinctive all white fur which is important
camouflage when hunting on the ice pack. Their actual color of the
skin is black which is thought to be an adaptation for better heat
retention. Compared to the other bears, the neck of polar bear is
much longer. This makes it easier for them to keep their heads above
water when swimming. Like those of other bears, the ears of the polar
bear are round. They are, however, smaller and closer to the head.
This also helps the animal to be an exceptional swimmer. The forepaws on a
polar bear are very large. With a diameter approaching 12 inches and
partial webbing between their toes, polar bears are able to use their
front feet much like paddles to propel them rapidly through the water.
Polar bears are excellent swimmers. They are able to swim distances
greater than 60 miles without a pause to rest, maintaining average
speed of 6 miles per hour. On land, they are not as quick as brown
bears and appear to have traded off speed for their extremely massive forelegs which they use to break through seal dens and to flip a large seal out of the water.
Polar bears have also developed large stomachs with a capacity of more than 150 pounds of food. Their digestive system is also more adapted for processing meat than plant material because they are almost exclusively meat eaters. While out on the ice, their diet consists mostly of marine mammals such as the ringed seals, bearded seals and occasionally a walrus or narwhal. Also, in keeping with their carnivorous nature, the canine teeth, used for seizing and holding prey, are longer, sharper and spaced wider apart than in brown bears.
Polar bear are at the top of the arctic food chain with no natural
enemies. Because of that, compared to other bears, polar bears are the
most aggressive and more willing to consider humans as a prey. In
other words, when they see a human, they see a walking meal.
Consequently the person attacked is usually killed unless the bear is
killed first. The most carnivorous, they are also the most patient and determined all of bears. In some instances they may follow a person for hundreds of miles in order to hunt him down. Out of eight species polar bear is considered to be the most dangerous to human beings.
The brown bear has the most widespread distribution in the world of
any of the eight bear species. They are found throughout most of the
northern hemisphere including North America and Eurasia. Their
preferred habitat includes mountain forests, open meadows and large
river valleys. It is estimated that there are currently somewhere
between 125,000 to 150,000 brown bears throughout the world.
The brown bear is one largest bear species, yet considerably smaller
than the polar bear. It weighs between 300 and 860 and can be up to 9.5
feet in total body length depending on the availability of food.
Brown bears can run and climb with considerable skill, speed and
dexterity. They are able to attain speeds of 35 mile per hour for a
short distance. They are also capable swimmers.
The brown bear distinguishes itself from other bears by virtue of
its shoulder hump, which is caused by muscles which are used for
digging. The front claws are approximately 1.7 times longer than the
rear claws and generally visible even from distance. The color of the
animal varies from a light creamy color to almost black.
Brown bears are omnivorous, eating a mixed diet of grasses, fruits,
bulbs and roots, insects, fish and small animals. In few areas there
are known to be predators of larger animals such as caribou and moose.
Each of the brown bears has a different temperament rather like
humans. Some will attack, others will not. Some bears are scared of
humans, others will have a have natural curiosity. Brown bears may be
very dangerous. However, most of the time a they more likely to
attack when defending cubs or territory. A stalking brown bear is even
a more rare occasion.
Even though polar and brown bears have a lot in common they differ in
many ways such as amount of population, size, areas of living, physical
characteristics and attitudes towards people. Scientists have studied these
magnificent animals for many years, but there is still much to learn about
them. They are very complex and fascinating creatures that deserve great
respect.
Bibliography
no biography