Narwhal (Monodon monoceros): Facts, Tusk and Habitat

What does a narwhal look like?

A narwhal has a stocky, torpedo-shaped body, a small rounded head with a bulging forehead and a short, blunt mouth. Instead of a dorsal fin it has a low, uneven ridge along its back, which may help it swim and surface under sea ice. Its flippers are short and turn up at the tips, and the tail flukes of adult males are shaped differently from those of females, possibly to balance the drag of the tusk.

The skin is mottled. Newborn calves are a fairly even blue-gray, and as narwhals age they develop a spotted pattern of black or dark brown over a cream or white background. Very old narwhals can become almost white. The name comes from Old Norse and is usually translated as “corpse whale,” possibly because the mottled skin reminded sailors of a drowned body.

The narwhal’s closest relative is the beluga whale. The two are the only living members of the family Monodontidae, and both have rounded heads, a bulging forehead and no true dorsal fin.

How big is a narwhal?

Narwhals are mid-sized whales, much smaller than a humpback or sperm whale. Adults measure about 3–5.5 m (10–18 ft) from snout to tail, not counting the tusk, and males are clearly larger and heavier than females. About a third of their body weight is blubber, a fat layer 5–10 cm (2–4 in) thick that keeps them warm in near-freezing water.

The narwhal tusk

The famous tusk is not a horn but a tooth. Apart from a few tiny leftover teeth, narwhals have only two teeth, both upper canines embedded in the jaw. In most males the left one begins to grow out through the upper lip when the whale is two or three years old and keeps growing for life, forming a straight, hollow shaft with a left-handed spiral. It usually reaches 1.5–3 m (5–10 ft).

A few males grow two tusks, and a minority of females grow one, usually shorter than a male’s. The tusk contains millions of nerve endings, and scientists have suggested it may sense changes in the water. Most researchers agree that its main role is as a signal of quality and status, like a stag’s antlers: males with bigger tusks are probably more attractive to females and more dominant over rivals. Males are often seen gently rubbing or crossing their tusks above the surface, a behavior called tusking.

In 2016, drone footage from Tremblay Sound in Nunavut showed narwhals tapping Arctic cod with their tusks to stun them before eating. Find out more in What is a narwhal tusk?

Where do narwhals live?

Narwhals live only in the Arctic, mostly in the Atlantic sector between about 60° and 85° north. The great majority are found in the Canadian Arctic Archipelago, Baffin Bay, Davis Strait and northern Hudson Bay, and along the coasts of West and East Greenland. Smaller numbers live around Svalbard, Franz Josef Land and parts of the Russian Arctic. They are rare visitors to Alaska and are absent from the Antarctic.

Their year follows the ice. In summer, narwhals gather in ice-free coastal bays, fjords and inlets, often returning to the same places every year. In autumn they migrate offshore, sometimes more than 1,000 km (620 mi), to spend the winter in deep water covered by dense pack ice, where open water may cover only a few percent of the surface. Read more in Where do narwhals live?

What do narwhals eat?

Narwhals are carnivores with a narrow diet. Their main prey are Greenland halibut, a large flatfish of the deep seafloor, along with Arctic cod, polar cod, Gonatus squid and shrimp. Stomach studies also turn up occasional wolffish, capelin and even pebbles swallowed while feeding near the bottom.

With no working teeth in the mouth, narwhals probably catch prey by swimming close and sucking it in. Most feeding happens in winter, when they hunt intensively on the wintering grounds. In summer their stomachs are often nearly empty, which suggests they eat much less during the ice-free months.

Deep diving under the sea ice

Narwhals are some of the deepest-diving mammals on Earth. On their wintering grounds in Baffin Bay and Davis Strait, satellite tags show them diving to at least 800 m (2,600 ft) 15–25 times a day for months on end. Over half of these deep dives reach about 1,500 m (4,900 ft), and the deepest recorded reach roughly 1,800 m (5,900 ft) or more. A deep dive lasts up to about 25 minutes.

Several adaptations make this possible. Narwhal muscles are packed with myoglobin, a protein that stores oxygen, and they rely on slow, oxygen-saving muscle fibers suited to endurance rather than speed. A flexible rib cage allows the lungs to collapse under pressure. Under the ice, narwhals must also find cracks and breathing holes, probably using echolocation.

Behavior and communication

Narwhals are social whales. They usually travel in small groups of a few animals, often 3–8, sometimes made up of females and young or of adult males. In summer and during migration, groups merge into gatherings of hundreds and occasionally more than a thousand.

Like dolphins and other toothed whales, narwhals navigate and hunt by echolocation, producing rapid clicks and listening to the echoes. They also make whistles, pulsed calls and knocking sounds to keep in touch, and calls within a group can be more similar to each other than to those of other groups. At the surface narwhals are often quiet and still, a behavior called logging.

Reproduction and lifespan

Narwhals mate among the offshore pack ice in early spring, roughly March to May. Pregnancy lasts about 14–15 months, and a single calf is born in late spring or summer of the following year. Calves nurse for around 20 months, and females usually give birth every two to three years. Females become mature at about 6–9 years old, and males somewhat later.

Narwhals are long-lived. Many live 50 years or more, and studies of amino acids in the eye lens suggest some reach far greater ages: one female from West Greenland was estimated at about 115 years, with an uncertainty of around 10 years. Narwhals are also among the few mammals in which females live for many years after they stop breeding, a trait shared with orcas, belugas and a few other toothed whales.

Predators and threats

Narwhals have two main natural predators. Orcas hunt them in open water, and narwhals often escape by moving close to shore or hiding among ice floes. Polar bears sometimes catch them at breathing holes. When the sea freezes suddenly in autumn, groups can become trapped in small openings far from open water, an event known by the Greenlandic word savssat, and many may die.

Climate change is their biggest long-term threat. Narwhals depend on predictable sea ice and are considered one of the Arctic mammals most sensitive to its loss. Less ice also brings more orcas into Arctic waters, along with more ships, noise, seismic surveys and industrial development. Pollution, especially mercury and other contaminants that build up in the food chain, is another concern.

Narwhals are also hunted for food by Inuit communities in Canada and Greenland, under quotas meant to keep the harvest sustainable.

Conservation status

The IUCN Red List classifies the narwhal as Least Concern, based on a 2017 assessment that estimated about 170,000 animals worldwide, including around 123,000 mature individuals. However, population trends are uncertain, some smaller populations in East Greenland are a conservation concern, and narwhals are listed as a species of Special Concern in Canada.

International trade in narwhal tusks and other products is controlled under Appendix II of CITES, and the United States has banned imports of narwhal products since the Marine Mammal Protection Act of 1972.

Narwhals and people

For Inuit in Canada and Greenland, the narwhal has been an important animal for thousands of years. Muktuk, the skin with its layer of blubber, is a traditional food rich in vitamin C, which is otherwise hard to find in the Arctic. In one Inuit story, a woman tied to a harpoon line was pulled into the sea and became the first narwhal, her twisted braid turning into the tusk.

In medieval Europe, narwhal tusks traded south from the Arctic were sold as unicorn horns. They were believed to neutralize poison and were worth far more than their weight in gold, decorating royal treasuries and the Danish coronation throne. Narwhals have never survived long in captivity, so the only way to see one alive is in the wild. Learn how the unicorn myth began in Are narwhals real?