The Narwhal, Monodon monoceros, is a social, specialized deep-water marine mammal characterized by a unique tooth growth protruding from the upper jaw. Narwhals lives along the coasts and rivers throughout the Arctic,characterized by icy ocean temperatures. Narwhals are usually found in groups of 15 to 20, but herds of several thousand have been seen in the Arctic waters since 1871. Regularly found eastwards from the Canadian Arctic to central Russia they have also been distributed throughout the Eurasian Arctic and in an especially high abundance around the oceans west of Cape Farewell on the east coast of Greenland in the summers and during the winter primarily in the Baffian Bay, and in the Canadian archipelago in the springtime (Reeves, Tracey). The Narwhal has two teeth, located in the upper jaw, however only the left tooth usually develops leaving the underdeveloped right tooth in males and typically both teeth in females vestigial (Das). The protruding tusk grows to about 3 meters forward in a counterclockwise spiral pattern (Drury). The distal end of the tusk appears polished, with the remainder commonly covered by a growth of algae. There is an outer layer of cement, an inner layer of dentine, and a pulp cavity that is rich in blood (Reeves, Tracey). The Narwhal’s head and body ranges from 3-6 meters, with the pectoral fin being around 30-40 cm, and the tail flukes expanding over one meter (Reeves, Tracey). The males are typically larger in size than the females averaging about 3,500 pounds in males and 1,000 in females (Drury). Their bodies begin as an uneven grayish hue and as they mature darken to a mottled bluish black color, darker above than below (Reeves, Tracey). Narwhals posses relatively small heads, a blunt sno...
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...ility probably advanced early in the development of life to counter cellular degradation.
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Isle Royal is located fifty-six miles north of Michigan’s Keweenaw Peninsula. It is the largest wilderness area in Michigan (USNPS, 2014). The island is surrounded by Lake Superior, which creates a cooler temperature. This results in arctic plant species growth on the island. There are only eighteen mammal species present on the island because most mammals cannot make the trip across the frozen great lake (USNPS, 2014). The need for an ice bridge is not the only environmental factor that is stopping the migration of animals; there is also the severe cold, and also wind and fog (Vucetich, 2012). Some species such as caribou and coyote have found the island to be too intense and have gone extinct (Vucetich, 2012). Due to the harsh weather and isolation of the island, humans have never regularly lived on the island (Vucetich, 2012). Some of species that are present such as the red squirrel are becoming their own subspecies due to its separation from the mainland (USNPS, 2014). The isolation of Isle Royal is what makes it a great place to conduct research, it has very low human interaction and the species that are on the island will have been and continue to be isolated from the mainland.
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This essay discusses the evolution of amphibians. Amphibians are classified into three orders (anura, caudata and apoda) and are in the superclass tetrapoda (Kolesova, et el, 2007). The Apoda is comprised of organisms with no legs, and these organisms normally live in barrows. Tretrapods are comprised of vertebrates with four limbs; and examples of tetrapods are reptiles and amphibians (Kolesova, et el, 2007). Tetrapods were the earliest vertebrates to be able to walk on land and that was during the Devonian period about 360-370 million years ago (Kolesova, et el, 2007). Before the existence of amphibians almost all vertebrates lived in water (Kolesova, et el, 2007).