Taxonomy & Nomenclature
Physical Description / Field Identification
Narwhals are characterized by a robust body, relatively small, bulbous head with little or no beak, short blunt flippers that curl up at the tips in adults, absence of a dorsal fin (however, a slight dorsal ridge is present), and oddly-shaped flukes. The flukes of adults become straight to concave on the leading edge, and convex on the trailing edge. They are deeply notched and the tips tend to curl upwards, especially in older animals.
Young narwhals are uniformly gray to brownish gray. As the animals age, they darken to all black and then mottling develops. At this stage they appear spotted and the belly becomes light gray to white (with some dark mottling). Older animals often appear nearly white, with some black still remaining on the upper surfaces and appendages.
There are only two teeth, both in the upper jaw. In females, these almost always remain embedded in the upper jaw bones, but in males the left tooth normally grows out through the front of the head and becomes a tusk up to 3 m long. Occasionally, females with a tusk or males with two developed tusks are seen.
Adult females can be up to 4.2 m and males up to 4.8 m long. Large narwhals can reach weights of over 1600 kg. Narwhals are about 1.6 m long at birth.
Can be Confused With
The narwhal is likely to be confused only with the white whale. Young white whales, especially, can look like narwhals, because of their gray coloration. The absence of blotching or spotting on white whales is probably the best guide, and male narwhals can be easily distinguished by their tusks.
Distribution
This is a panarctic species; it is found mostly above the Arctic Circle year-round. The principal distribution of the narwhal is from the central Canadian Arctic (Peel Sound and northern Hudson Bay), eastward to Greenland and thence to the eastern Russian Arctic (around 180°W). They are rarely observed in the far eastern Russian Arctic, Alaska, or the western Canadian Arctic. There are annual migrations, primarily to open water in fall and back to inshore waters in spring. Five stocks are recognized on the basis of distribution and migration patterns.
Ecology and Behavior
Most pods of narwhals consist of 2-10 individuals, but there is some evidence that these groups are often parts of large dispersed herds of hundreds or even thousands of individuals. There is some age and sex segregation of narwhal groups, and all-male groups are common.
The tusk of male narwhals has long been a source of scientific controversy. It now is generally agreed that the tusk is used in male-male competition for females. It is used perhaps primarily as a display, although male narwhals have been seen "sparring" with their tusks above water.
Young narwhals are born mainly in summer, from July through August.
Feeding and Prey
Fish, squid, and shrimp make up most of the narwhal’s diet. They feed, at times, in deep water and possibly at or near the bottom. Dives of up to nearly 1,200 m and 25 min. are known.
Threats and Status
Although never the targets of large-scale commercial hunting, narwhals have been hunted by native peoples of the Arctic for their valuable tusks and highly sought-after flesh, which is eaten and used for dog food. While not endangered on a global scale, some populations may be depleted, and continue to be subjected to unsustainable exploitation.
Narwhals are prone to morality from ice-entrapments, which may be happening more frequently these days, at least partially due to human-induced climate changes. When live entrapped whales are discovered by Inuit hunters, they normally take advantage of the event by killing the animals. The tissues of narwhals contain high levels of environmental contaminants, although the specific effects of these are not known.
Narwhals are currently listed as ‘Data Deficient’ (IUCN) and ‘Not Listed’ (ESA).
Links
References
Born, E.W., R. Dietz and R.R. Reeves (eds). 1994. Studies of white whales (Delphinapterus leucas) and narwhals (Monodon monoceros) in Greenland and adjacent waters. Meddelelser om Gronland Bioscience< 39:1-259.
Hay, K.A. and A.W. Mansfield. 1989. Narwhal Monodon monoceros Linneaus, 1758. pp. 145-176 in S.H. Ridgway and R. Harrison, eds. Handbook of marine mammals, Vol. 4: River dolphins and the larger toothed whales. Academic Press.
Heide-Jorgensen, M.P. 2002. Narwhal (Monodon monoceros). pp. 783-787 in W. F. Perrin, B. Würsig and J.G.M. Thewissen, eds. Encyclopedia of marine mammals. Academic Press.
Reeves, R.R. and S. Tracey. 1980. Monodon monoceros. Mammalian Species 127:1-7.
Strong, J.T. 1988. Status of the narwhal, Monodon monoceros, in Canada. Canadian Field-Naturalist 102:391-398.
