The narwhal or Narwhale is a toothed whale. The scientific name of this whale is Monodon Monoceros. They are regularly found eastwards from the Canadian Arctic to central Russia. And they are also infrequently found in eastern Siberia, Alaska and the western Canadian Arctic. They mostly remain above the Arctic Circle year round, but stragglers have been recorded around New-foundland, Europe and the eastern Mediterranean.
Head and body length, exclusive of the tusk, is 360-620 cm, pectoral fin length is 30-40 cm, and expanse of the tail flukes is 100-120 cm. According to Reeves and Tracey (1980) average head and body length is about 470 cm in males and 400 cm in females and average weight is 1,600 kg in males and 900 kg in females. About one-third of the weight is blubber. Coloration becomes paler with age. Adults have brownish or dark grayish upper parts and whitish underparts, with a mottled pattern of spots throughout. The head is relatively small, the snout blunt, and the flipper is short and rounded. There is no dorsal fin, but there is an irregular ridge about 5 cm high and 60-90 cm long on the posterior half of the back. The posterior margins of the tail flukes are strongly convex, rather than concave or straight as in most cetaceans.
There are only two teeth, both in the upper jaw. In females the teeth usually are not functional and remain embedded in the bone. In males the right tooth remains embedded, but the left tooth erupts, protrudes through the upper lip, and grows forward in a counterclockwise spiral pattern to form a long, straight tusk. The tusk is about one-third to one-half as long as the head and body and sometimes reaches a length of 300 cm and a weight of 10 kg. In rare cases the right tooth also forms a tusk, but both tusks are always twisted in the same direction. Occasionally one or even two tusks develop in a female. The distal end of the tusk has a polished appearance, and the remainder is usually covered by a reddish or greenish growth of algae. There is an outer layer of cement, an inner layer of dentine, and a pulp cavity that is rich in blood. Broken tusks are common, but the damaged end is filled by new dentine growth.
Narwhals have a varied diet, feeding upon squid, fish and crustaceans. With few functional teeth this animal is thought to use suction and the emission of a jet of water to dislodge prey such as bottom-living fish and molluscs. Their highly flexible necks aid in scanning a broad area and the capture of more mobile prey.
Foods eaten include: Polar cod, Greenland halibut, flounder, salmon, herring, crustaceans and cephalopods (octopuses and squids).
Historically narwhals were a staple food source of many Arctic peoples. Arctic people used the narwhals body for a number of other uses. The blubber can be rendered for oil, the sinew used as thread, and the tusks traded and carved.
Natural enemies include Greenland sharks (Somniosus microcephalus), orcas, polar bears and walrus, although the mortality rates inflicted by these species do not seem to be very high (Born, 1994). The same author reports that narwhals do occasionally become trapped in fast forming ice and may die during the winter because of exhaustion in an attempt to keep the breathing hole open.
http://en.wikipedia.org/wiki/Narwhal
http://animaldiversity.ummz.umich.edu/accounts/Monodon_monoceros/
http://www.iucnredlist.org/details/13704/0
http://www.cms.int/reports/small_cetaceans/data/M_monoceros/m_monoceros.htm