Narwhal

The male narwhal's horn helps explain the unicorn myth in medieval Europe. These porpoises sometimes fence with their horns, using them like swords. The function of the male’s long tusk is not fully understood. It may be used as a hunting implement, or as a tool to break up ice and create breathing holes for the whales. However, the most favoured explanation is that the males use their tusks to joust with each other, fighting over access to females during the breeding season.

The narwhal’s swollen forehead is known as its melon - a feature shared with dolphins and other toothed whales. The melon serves to focus the ultrasonic clicks that narwhals and other small cetaceans use to navigate and find their food. As in a sophisticated sonar system, the narwhals listen for the high-frequency echoes that rebound off nearby objects. So sensitive is this method of orientation that narwhals can not only distinguish between food and non-food items, but they can also tell the size of an object, how far away it is and how fast it is moving. These porpoises live in small groups, but may occasionally congregate in much larger groups, numbering thousands of individuals.

The male narwhal's tusk is in fact a greatly elongated front tooth that spirals as it grows from a hole in the whale's lips. It can reach 267 cm (105 in) long. Females may possess a short tusk, too. The name narwhal means "corpse whale", perhaps referring to the deathly hue of their white-blotched, bluish-grey skin. Their unusual name may referring to the way in which they often swim upside down.

Distribution: Found in the far north, in eastern Canada and around much of the coast of Greenland, extending across the polar region north of Europe and Asia.

Habitat: Coastal Arctic waters. Food: Cuttlefish, fish, crustaceans and squid.

Weight: 907 - 1587 kg (2000 - 3500 lb); males are much bigger.

Length: 4 - 4.6 m (13 - 15 ft).

Maturity: Females 4 - 7 years; males 8 - 9 years.

Gestation Period: Around 465 days; calves are brown at birth.

Breeding: 1; weaning may take 2 years.

Diet: Includes fish such as Arctic cod, plus squid, octopus and crustaceans.

Lipespan: Up to 50 years.

Status: Common.

Appearance

Heavily mottled on the upperparts of the body, these porpoises are paler on the flanks and underside. Old males become mainly white.

Ridge

There is no dorsal fin in these cetaceans, but a ridge extends down the middle of the back.

Flippers

These are relatively short and broad.

Tusk

Tightly spiralled in shape, the tusk is occasionally evident in females, but is shorter than in males.

DANGEROUS LIVING

Narwhals may fall victim to attacks by killer whales. They can also sometimes drown after becoming trapped under the ice.

The male's tusk grows most rapidly after sexual maturity.