Narwhal

The Narwhal (Monodon monoceros) is an Arctic species of cetacean with a body similar to that of a Beluga whale and Irrawaddy Dolphin. It is rarely found south of latitude 70°N. It is one of two species of whale in the Monodontidae family (the other is the beluga whale). It is possibly also related to the Irrawaddy dolphin.

The name "Narwhal" is derived from the Old Norse word náhvalr, meaning "corpse man". This probably is a reference to the mottled white and grey colouring of the skin of the adult. It may also refer to the way a narwhal can lie belly up, motionless, for a few minutes at a time.

Physical description

The most conspicuous characteristic of male narwhals is their single extraordinarily long tusk, which is a tooth that projects from the left side of the upper jaw and forms a left-handed helix. The tusk can be up to 3 m (nearly 10 ft) long (compared with a body length of 4–5 m ^*) and weigh up to 10 kg (22 lb). One in 500 males has two tusks, which occurs when the right tooth, normally small, also grows out. Rarely, a female narwhal may also produce a tusk.

The purpose of the tusk has been the subject of much debate. Early scientific theories supposed that the tusk was used to pierce the ice covering the narwhal's Arctic Sea habitat. Others suggested the tusk was used in echolocation. More recently, scientists believed the tusk is primarily used for showmanship and for dominance: those males with the largest tusk are most likely to successfully attract a mate. This hypothesis was suggested by the activity of "tusking", in which two males rub their tusks together.

However, recent work by a research team led by Martin T. Nweeia suggests that the tusk may in fact be a sensory organ. Electron micrographs of tusks revealed millions of tiny, deep tubules extending from the tusk's surface, apparently connecting to the narwhal's nervous system. While such tubules are present in the teeth of many species, they do not typically extend to the surface of healthy teeth. The exact sensory purpose of the tusk remains unknown, but scientists now hypothesize that it may detect temperature, salinity, pressure, and/or particulate makeup of the water in which the narwhal swims^*.

Like the tusks of elephants, narwhal tusks do not regrow if they break off.

Male narwhals weigh up to 1,450 kilograms, the female around 900 kilograms. Most of the body is pale with brown speckles in colour, though the neck, head and edges of the flippers and fluke are nearly black. Older animals are usually more brightly colored than younger animals.

Behavior & diet

Narwhales are quick, active mammals which feed mainly on species of cod that reside under ice-enclosed seas. In some areas their diet seems to have adapted to feed on squid, shrimp, and various fish, such as schooling pelagic fish, halibut, and redfish. Narwhals normally congregrate in groups of about five to ten. Sometimes several of these groups might come together, particularly in summer when they congregate on the same coast. At times, male narwhales rub their tusks together in an activity called "tusking". Recent findings of a marine mammal researcher at the Smithsonian Institution, finding that the tusk also plays a role in the animal's sensory perception, with as many as 10 million tiny nerves present within the modified tooth, suggests that the tusking may simply be a way of clearing encrustations from the sensory tubules, sort of like brushing teeth.

Narwhals are deep divers. During a typical deep dive the animal will descend at two metres per second for eight to ten minutes, reaching a depth of up to 1000 m, spend perhaps a couple of minutes at depth before returning to the surface. The deepest recorded is 1164 m. Typical dive times are 20 minutes, with 25 minutes recorded in exceptional cases.

Population and distribution

The narwhal is found predominantly in the Atlantic and Russian areas of the Arctic. Individuals are commonly recorded in the northern part of Hudson Bay, Hudson Strait, Baffin Bay, off the east coast of Greenland and in a strip running east from the northern end of Greenland round to eastern Russia (170°E). Land in this strip includes Svalbard, Franz Joseph Land, and Severnaya Zemlya. The northernmost sightings of narwhal have occurred north of Franz Joseph Land, at about 85°N.

Estimates of population have concentrated on the fjords and inlets of Northern Canada and western Greenland. Aerial surveys suggest a population of around 40,000 individuals. When submerged animals are also taken into account, the true figure may be in excess of 50,000.

Narwhals are a migratory species. In summer months they move closer to coasts. As the winter freeze begins, they move away from shore, and reside in densely-packed ice, surviving in leads and small holes in the ice. As spring comes these leads open up into channels and the whale returns to the coastal bays.

Predation and conservation

The main predators of the narwhal are polar bears and orcas. Inuit people are allowed to hunt this whale species legally. In Greenland, traditional hunting methods in whaling are used (such as harpooning), but high-speed boats and hunting rifles are frequently used in Northern Canada. PETA and other animal rights groups have long protested the killing of narwhals.

The Narwhal in culture

In Inuit legend, the narwhal was created when a woman holding onto a harpoon had been pulled into the ocean and twisted around the harpoon. The submerged woman was wrapped around a beluga whale on the other end of the harpoon, and that is how the narwhal was created.

Some medieval Europeans believed narwhal tusks to be the horns from the legendary unicorn. Considered to have magic powers, Vikings and other northern traders sold the tusks for many times their weight in gold. The horns were used to make cups that were thought to negate any poison that may have been slipped into the drink. During the 16th century, Queen Elizabeth received a narwhal tusk for £10,000 - the cost of a castle, which she used as a scepter.

Unicorns are often depicted with horns with a spiral pattern markedly similar to the narwhal's tusk.

The truth of the tusk's origin developed gradually during the Age of Exploration, as explorers and naturalists began to visit Arctic regions themselves. In 1555, Olaus Magnus published a drawing of a fish-like creature with a horn on its forehead, while in 1577, Martin Frobisher depicted the horn going forward. The definitive end to the legend came in 1638, when Danish zoologist Ole Wurm gave a public lecture on the narwhal's tusks.

In Jules Verne's novel Twenty Thousand Leagues Under the Sea, the submarine Nautilus is initially believed to be an unclassified subspecies of Narwhal.

In the comedy Elf , Santa elf Buddy, played by Will Ferrell, runs across a talking Narwhal that says "Bye Buddy. Hope you find your dad" when Buddy says, "Bye Mr. Narwhal."

Pictures

Image:Narwal brehm.jpg|Narwhal drawing Image:Narwal.jpg Image:Narwhal and Beluga.jpg

References

Database entry includes justification for why this species is listed as data deficient
"Narwhal." M. P. Heide-Jorgensen (pp 783–787), in Encyclopedia of Marine Mammals, Perrin, Wursig and Thewissen eds. ISBN 0125513402
"It's Sensitive. Really." William J. Broad, New York Times, 13 December 2005, http://nytimes.com/2005/12/13/science/13narw.html / NYT article RSS link
Narwhal general information
Narwhal Tooth Expedition and Research Investigation
Narwhal info
Some Of Drewmo's Cartoons Have Narwhals In Them
"Narwhal Found to Have a Trick Up Its Tusk", Scientific American News

External link

ARKive - images and movies of the narwhal (Monodon monoceros)

Arctic cetaceans | Toothed whales

Gourt Home::Gourt :: Narwhal