Narwhal Whales Term Paper
- Length: 6 pages
- Subject: Animals
- Type: Term Paper
- Paper: #12964377
Excerpt from Term Paper :
The Narwhal or monodon monoceros is a rarely seen arctic whale. Its name is derived from the Norse, meaning 'corpse whale' due to its grayish appearance while floating in the water. (American Zoo) Narwhal whale's are described as having 'small rounded heads, short flippers with upturned tips, and no dorsal fin but an uneven dorsal ridge along the spine'. (Whale guide Reference Desk: Narwhals) The males are larger than the females and the largest of the species measures 16 feet or 4.9 meters on average and weigh 1.8 tons (1.6 tonnes). At birth a Narwhal usually measures about 5 feet (1.5 m) in length and weighs 175 pounds (80 kg). (All about Whales) The color of adult Narwhals is mottled grey but the older Narwhals are generally pure white.
Narwhal whales are usually located in the arctic seas at the latitudes of 700 North and 800 North. . They are also found 'eastwards from the Canadian Arctic through much of Russia. The populations found here are most abundant'. (ibid) They are usually found near ice and in deep fjords. Narwhals are rarely seen in the winter months due to the adverse weather conditions in these regions and the poor visibility. (Whales, Dolphins, and Porpoises) They are however very visible at sea and easily distinguishable from other cetaceans due to the Narwhals' characteristic tusk to tooth. Narwhals are sometimes confused with the Beluga whales. (monodon monoceros: Narwhal)
These whales are capable of diving and remaining underwater for up to twenty minutes. They are also very vocal and make a wide range of noises and sounds for communication and navigation. There are wide variations in the clicks and whistles that these whales emit. Click Amplitudes range from 19 kHz to 48 kHz and the click rates vary from 3-150 clicks/sec; with Whistle amplitudes from 300 Hz to 18 kHz. (Secrets of the tusk)
Their normal lifespan is approximately fifty years and their usual diet consists of fish, squid and shrimps and various other forms of marine life. With regard to population figures it is estimated that there are approximately 10,000 to 45,000 Narwhals in existence. However, they are also the prey of man, and various natural predators such as polar bears and sharks. Narwhal whales are on the endangered species list. Their numbers have 'dropped by an average of 6% per year during the last 17 years." (Narwhals: Photos Show Decline of "Unicorn" Whales)
The most prominent characteristic of these whales is the tooth or horn that the males display, which is in fact an overgrown upper central incisor tooth, generally the one on the left. This is a rare phenomenon in the animal kingdom. Other than these teeth the animal is toothless. The tooth or long 'horn' can grow as long as ten foot (three meters) in length. The genus-species name of the whale means 'one tooth, one horn'. (Narwhal Whales)
Narwhal Whales have an unusual dentition. The species has two teeth with the roots in the upper jaw. Females' teeth are almost embedded, which makes them practically toothless. In males, one of the two teeth grows through the upper lip in a form of a tusk. The tusk is long and straight. The Narwhal's tusk is about 1/3 or more as long as the total body. It can weigh up to 10 kilos. (ibid)
After the first year a male Narwhal's left tooth begin to grow upward in a spiral shape. The tusk to tooth has a hollow interior. The function of the tusk is uncertain. Some suggest that it may be used either as a weapon, that may be used in courtship. It might also be used for "channeling and amplifying sonar pulses (which they emit)." (All about Whales)
Although the use of the tusk is not certain it has been ascertained that it is not used for hunting. Another misconception is that Narwhals use their tusks for breaking the ice to create breathing holes. Biologists disagree with this assessment and state that "for the most part Narwhals keep breathing holes open by simply using them a lot and preventing them from freezing up." (Odontoceti.)
In terms of their biological classification the Narwhal or Monodon monoceros (Suborder Odontoceti) is one of 76 cetacean species. Their full classification is as follows.
Kingdom Animalia (animals)
Phylum Chordata (vertebrates)
Class Mammalia (mammals)
Order Cetacea (whales and dolphins)
Suborder Odontoceti (toothed whales)
Superfamily Delphinoidea (oceanic dolphins and some whales)
Family Monodontidae (Narwhals and Beluga whales)
(All about Whales)
There are several families of Odontoceti, or toothed whales. These include sperm whales, pygmy sperm whales, beaked whales, as well as belugas and Narwhals, dolphins and porpoises.
2. General biology and behavior
The Narwhal is a social animal living in pods or groups of two to ten individual whales. They also tend to travel in groups. (American Zoo) These groups are often ordered according to gender. There are also pods which consist only of male bachelors. In the breeding season Narwhal whales have been seen to congregate in groups as large as 50. During this time a form of behavior known as 'fencing' takes place. "Fencing is a sexual display put on by males to compete for females. The size of tusks (often used in violent battles) will define the hierarchical status of males in a group." (Odontoceti) There also seems to be strict segregation of the groups according to gender and age. These are usually divided into immature males, mature females and calves, and large adult females. (ibid)
The Narwhal occasionally travel and mix with the Belugas; large groups numbering hundreds or thousands have been reported. (ibid)
Their method of eating is to create a vacuum to 'suck up' their food which includes "squid, Greenland halibut, shrimp, Arctic cod, rockfish, flounder, and crab." (Whale guide Reference Desk) The male Narwhal's tusk is not thought to have any function with regard to feeding as the female also consumes the same food selection as the male.
The following fish are commonly eaten by the Narwhal: squid (most commonly Gonatus fabricii) and shrimps. Commonly taken fish include Boreogadus (Arctic Cod), Arctogadus (Polar Cod) and Reinhardtius (Greenland Halibut).
The female Narwhal is able to reproduce after five years and males at eight years of age respectively. Calves conceived in mid-April are born in July of the following year. A newborn calf is about five feet long. The normal birth cycle for female Narwhals is every three years.
Very little is known about the social life of these animals as they are often secretive and not easy to observe. The only real animal predator of Narwhals is the killer whale that journeys up to the Arctic regions where the Narwhals spend a great deal of their time.
4. The influence of man
Man has had a critical effect on the lives, and continued existence of the Narwhal whales and is one of the root causes for the reduction in population. The whales are hunted in various ways in Canada and Greenland. The Inuit people value the skin, known as mattak or muktuk. The tusk of the whale is also regarded as a valuable commodity and tourists pay well for this trophy. At one time about 3,000 Narwhals were caught per annum in Canada alone, and in the whaling season of 1914/15 some 2,000 animals were killed in Greenland. (monodon monoceros: Narwhal)
An interesting fact about these creature is that Narwhals are one of three whale species that spend their entire lives in the Arctic -- the others being bowhead and beluga whales. (Whale guide Reference Desk.) Narwhals are also seen by many experts to be the basis of the legends of the unicorn, due to its characteristic extended tooth or horn. However, these fascinating and important creatures have also been the object of a sustained hunt by man for their blubber and meat but mainly for their unique horn. This attack on the Narwhal is recorded as far back as the sixteenth century. However, with more sophisticated and modern means of killing, the threat to the whale has worsened over there years. "Today the market is vastly expanded; money is more widespread and animals are easier to find and kill - resulting in far greater damage to nature." (Bruemmer, Fred)
The threat to these fascinating and mysterious creatures is all the more tragic due to the fact that research into their anatomy and lives are still ongoing. This is particularly the case with regard to the research into the functioning of the Narwhal tooth which is being investigated as a sensory organ.
Because the expression of the Narwhal tusk contradicts predictable patterns, and because there is a lack of evolutionary information to describe its modern day features, it is likely that there is a valuable insight to be gained from understanding this uniquely odd example in nature.
The possibility of a tooth as a sensory organ may help explain many characteristics of this tooth in the…