Monday, October 5, 2015

The Bear & The Circulatory System

There are more than 8 million species living on earth currently, but this number is always in counting. The beautiful thing is that not all species are vastly different. Many are in fact the same animal, bred differently to fit the needs of their environment. Darwinism at its finest. For example, take the bear. When somebody says 'bear', many of us think grizzly or brown or even a thick forest in the mountain somewhere. If this is true of 'bears', what are Polar and Panda Bears? The reality is, they are all the exact same bear, with different attributes to help them survive in the region they inhabit.

The Grizzly Bear is the largest subspecies of the Brown Bear and is most prevalent in the US and Canada. Their appearance is specific in that they have developed a large hump on their back, as well as a 'dished in' face and round ears. Currently, the Grizzly Bear numbers 58,000 and is the fastest growing bear species cross-continentally.

The Polar Bear lives in areas of the world very few other animals are able to survive. They are a marine mammal and have evolved adaptations for Arctic life, such as large furry feet with sharp, stocky claws that give them good traction on ice. They are the one species of bear impacted by global warming the most, decreasing their population drastically.

Native to South Central China, the Panda Bear has developed a black and white spotted coloring, which is speculated to be due to the need for camouflage in their environment. The Panda is higher endangered merely due to their reduced habitat and reproductive habitats in captivity.

The circulatory system of the generic bear works very similarity to that of a human. The bear has a 4-chambered heart, in which blood comes in the right side and enters the lungs to be oxygenated. The left side of the heart pumps the oxygenated blood to the rest of the body via the left atrium, left ventricle and aorta. This is the same for humans. The difference lies in the path of the blood after the heart. The bear has more veins, meaning more valves. Since humans stand on two legs, transfer of blood to the body is simple. With the bear, the increased amount of valves allow a more fluid flow of blood to the mammal, as they are on four legs.

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