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.
Work Cited
Lindahl, Karen, and Susie Balser. "Tardigrade Facts." Tardigrade Facts. Illinois Wesleyan University, 2 Oct. 1999. Web. 20 Feb. 2014.
Das, Darshana, John P. Dafferty, and Grace Young. "Tardigrade (animal)." Encyclopedia Britannica Online. Encyclopedia Britannica, 15 May 2013. Web. 21 Feb. 2014.
Das, Darshana, and John Higgins. "Narwhal (mammal)." Encyclopedia Britannica Online. Encyclopedia Britannica, 20 Dec. 2013. Web. 21 Feb. 2014.
Drury, C. "Animal Diversity Web." ADW: Monodon Monoceros: INFORMATION. University of Michigan, 2002. Web. 21 Feb. 2014.
Reeves, Randall R., and Sharon Tracey. "Monodon Monoceros." Mammalian Species127 (1980): 1. Print.
Wright, J. "Animal Diversity Web." ADW: Tardigrada: INFORMATION. University of Michigan, n.d. Web. 21 Feb. 2014.
Fox, R. 2001. Invertebrate Anatomy OnLine: Artemia Franciscana. Lander University. http://webs.lander.edu/rsfox/invertebrates/artemia.html, retrieved February 13, 2011.
3 Apr. 2014. The 'Standard' of the 'Standard'. http://eol.org/pages/323582/details>. Evans, Arthur V., Rosser W. Garrison, Neil Schlager, and Michael Hutchins. Grzimeks' Animal Life Encyclopedia.
The American Society of Mammalogists, . Mammalian Species: Alces alces. Vol. 154. 1981. 1-7. Web.
... middle of paper ... ... Larson, R. (1978). The Species of the World.
Mammals of Florida. Miami, Florida: Windward Publishing. 3. Land, Darrell, and Sharon K. Taylor. 1998.
15. Magers, Vince. Ichthyology’s Golden Age. Missouri Conversationist, Volume 60, Number 9, Sept 1999. http://www.conservation.state.mo.us/conmag/1999/09/6.html
U.S. Department of the interior, National Park Service. (2013). Endangered Species. Retrieved from website: http://www.nature.nps.gov/biology/endangeredspecies/index.cfm
Soule, Michael E et al. “Ecological Effectiveness: Conservation Goals for Interactive Species.” Conservation Biology 17.5 (2003) : 1238-1250.
Works Cited Bates, D. (1957, December 17). Letter from Roy Wilkins. Little Rock, Arkansas, United States of America. Beals, M. P. (1994). The Species of the World.
The "White-Tailed Deer." Ccontario.org. Cornell University, 2001. http://www.cnu.edu/item/cnu Web. The Web.
Mukerjee, Madhusree, Laurie Grace, and Bryan Christie. "Trends in Animal Research." Scientific American, 2 Feb. 1997: n. pag. elibrary. Web. 12 Nov. 2013.
Rees, P. A., 2013. Dictionary of Zoo Biology and Animal Management. West Sussex: John Wiley and sons .
Sikes, Roberts. and William L. Gannon. "Guidelines of the American Society of Mammalogists for the Use of Wild Mammals in Research." Journal of Mammalogy 92.1 (Feb. 2011): 235-253. Academic Search Premier. EBSCO. Web. 5 Oct. 2011.
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).