Narwhal

• 1. Introduction

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  The narwhal, Monodon monoceros, is a toothed whale of the Arctic, and the males carry a spiralled tusk that can stretch three metres. Why would a whale grow such a thing, and what is it for? The narwhal also spends much of its life in deep, freezing water, often beneath the ice. How does a stocky, blunt-snouted whale manage that? Its tusk once caught the eye of European rulers, who treasured it as something far stranger than a tooth. Today the animal's future depends on a changing Arctic, and on the Inuit who still hunt it.

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• 2. Names And Ancestors

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  In 1758, Carl Linnaeus described the narwhal in his Systema Naturae. The English name comes from the Old Norse nárhval, which means 'corpse-whale'. It may refer to the animal's mottled grey skin. It may also refer to logging, the habit of floating motionless at the surface, usually in summer. The scientific name comes from Ancient Greek and means 'single-tooth single-horn'.

  The narwhal's closest living relative is the beluga whale, Delphinapterus leucas. Together they are the only living members of the family Monodontidae. Members of the family share pronounced melons, short snouts and the lack of a true dorsal fin.

  Around 1990, the remains of an odd whale turned up in West Greenland. Marine zoologists said it matched no known species, with features midway between a narwhal and a beluga. A 2019 DNA analysis confirmed it as a hybrid, a so-called narluga. Whether such a hybrid could itself breed remains unknown.

  A genetic study places porpoises and monodontids together in a group that diverged from other dolphins about 11 million years ago. A 2018 analysis of monodontid fossils put their split from porpoises between 10.82 and 20.12 million years ago. A 2020 study using mitochondrial DNA suggested the narwhal parted from the beluga about 4.98 million years ago.

  In 2019, researchers described Casatia thermophila, from early Pliocene central Italy, as a possible narwhal ancestor. Other extinct relatives, Bohaskaia, Denebola and Haborodelphis, come from the Pliocene of the United States. Fossils show that early monodontids lived in tropical waters. They may have moved into Arctic and subarctic seas as the marine food chain changed. Those that stayed in the cold north ended up with a body unlike that of most whales.

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• 3. Built For Ice

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  Adults measure between 3.0 and 5.5 metres and weigh 800 to 1,600 kilograms. Males run about 70 centimetres longer than females and are more than 75% heavier. Females mature first, at 8 to 9 years old and about 3.4 metres long. Males take 12 to 20 years and reach 3.5 to 4.0 metres.

  Light grey skin marks a newborn narwhal. Adults wear blackish-brown mottling on a white background, and white patches spread from the navel and genital slit once they mature. The whitening continues for life, so very old narwhals look almost pure white.

  Where most whales have a dorsal fin, the narwhal has only a shallow ridge along its back. This may make swimming under ice easier, or help the animal roll. Its neck vertebrae are jointed rather than fused, which gives the neck unusual flexibility. The beluga shares both traits. The tail flukes differ by sex: in males they bend inward, while in females they sweep back along the front edge. This is thought to reduce the drag that a tusk causes.

  Deep foraging is powered by slow-twitch skeletal muscles that hold a reserve of oxygen, giving endurance and manoeuvrability. A high level of myoglobin also helps with deeper dives. Beneath the skin lies blubber 50 to 100 millimetres thick, which makes up a third of the body mass and insulates against the cold ocean. Muscles and blubber like these are put to the test far below the surface.

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• 4. The Tusk

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  Drone footage from August 2016 in Tremblay Sound, Nunavut, showed narwhals tapping small Arctic cod with their tusks and stunning them. The stunned fish were easier to catch. Feeding is only one of the proposed uses. Some biologists think narwhals fight with their tusks. According to Martin Nweeia, males rub the tusks together to clear off encrustations, rather than to stage displays of rivalry.

  The tusk is also a sensory organ, packed with millions of nerve endings. It lets the narwhal sense temperature variation around it. The nerves may also detect changes in particle concentration and water pressure.

  Females usually have no tusk, yet they live longer than males, so the tusk cannot be essential to survival. The accepted view is that it is a secondary sexual characteristic that signals social status, and that its main role lies in sexual selection.

  The tusk is a canine tooth that projects from the left side of the upper jaw. Both sexes have a pair of tusks embedded in the upper jaw, and in males the left one breaks through the lip at two to three years of age. It keeps growing throughout life, is hollow, and weighs up to 7.45 kilograms. Some males grow two tusks, when the right canine also pushes through the lip. Females rarely grow one, and when they do it is smaller, with less noticeable spirals.

  Beside the tusk sits a single pair of small vestigial teeth in open sockets in the upper jaw. Males commonly shed them in the palate. The varied shapes of these small teeth point toward evolutionary obsolescence.

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• 5. Dives And Migration

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  The deepest dive recorded for a narwhal reached 2,370 metres. In their wintering waters, narwhals dive to at least 800 metres more than 15 times a day, and many dives reach 1,500 metres. A single dive can last up to 25 minutes.

  Depth varies by place. In the southern Baffin Bay wintering grounds, narwhals dive deep along steep coasts. In the northern wintering grounds they dive less deeply, despite deeper water, because prey sits closer to the surface there.

  The species is found in the Atlantic and Russian sectors of the Arctic Ocean. Records come from the Canadian Arctic Archipelago, northern Hudson Bay, Hudson Strait, Baffin Bay and the east coast of Greenland. A strip also runs east from northern Greenland to eastern Russia, at 170 degrees east, taking in Svalbard, Franz Joseph Land and Severnaya Zemlya. The northernmost sightings were north of Franz Joseph Land, at about 85 degrees north. Around 140,000 narwhals live in Baffin Bay.

  In summer, narwhals move closer to the coast, often in pods of 10 to 100. In winter they retreat to deeper offshore waters under thick pack ice. They surface in narrow fissures or in wider fractures called leads, which open into channels each spring.

  Narwhals in Baffin Bay travel to northern Canada and Greenland between June and September. They then swim about 1,700 kilometres south to the Davis Strait and stay until April. There the pack ice holds less than 5% open water, and Greenland halibut are dense along the continental slope.

  The narwhal's diet is restricted and specialised. With poorly developed teeth, narwhals are believed to swim close to prey and suck it into the mouth. A study of 73 narwhals found Arctic cod most common in the stomachs, followed by Greenland halibut and large quantities of armhook squid. Males were more likely to have eaten polar cod and redfish, both found below 500 metres. In winter the whales feed on flatfish under dense pack ice, and they eat more then than in summer. Wolffish, capelin and skate eggs also turned up in stomachs, and sometimes rocks.

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• 6. Pods And Voices

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  Groups of three to eight narwhals are the norm. Some are nurseries of females and young, while others hold only juveniles or only adult males, called bulls. Mixed groups can form at any time of year. In summer, several groups merge into aggregations of 500 to over 1,000. Males have been seen rubbing each other's tusks, a behaviour called tusking.

  Courtship and mating have been recorded from March to May among offshore pack ice, and probably involve a dominant male mating with several partners. Gestation lasts about 15 months, and births are most frequent in July and August. Females have a calf every two to three years, and only one calf is born at a time, averaging 1.5 metres in length. Summer surveys along Baffin Island inlets found calves made up 0.05% of 35,000 narwhals in Admiralty Inlet but 5% of 10,000 in Eclipse Sound. This hints that some inlets serve as calving and nursery habitat.

  A newborn has only a thin layer of blubber, which thickens as it nurses on fat-rich milk. Calves depend on milk for about 20 months, giving them time to learn survival skills. Narwhals are among the few animals that go through menopause and live for decades afterwards. A 2024 study concluded that five toothed whale species evolved menopause to gain longer lives, while their breeding years stayed the same. Scientists suspect that calves are hard for one female to raise alone and benefit from help by older females.

  Like most toothed whales, narwhals use sound to navigate and hunt. They make clicks, whistles and knocks with air moving between chambers near the blowhole. Sound bounces off the sloping front of the skull and is focused by the melon, a mass of fat that muscles can control. Echolocation clicks find prey and barriers at short range, while whistles and throbs mostly pass messages between pod members.

  Calls from one pod resemble each other more than calls from different pods, which hints at group-specific or individual calls. Narwhals sometimes adjust the pitch and length of their pulsed calls to carry better in different acoustic settings. Trumpeting and 'squeaking-door sounds' are also on the list. The repertoire resembles the beluga's, but the frequency ranges, durations and repetition rates of narwhal clicks differ.

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• 7. People And Unicorns

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  At Qaanaaq in Greenland, hunters still harpoon narwhals from handmade kayaks. Elsewhere in Greenland and northern Canada, hunters use high-speed boats and rifles. Inuit have taken narwhals much as they take seals and other whales, using almost every part: meat, skin, blubber and organs. Muktuk, the raw skin with its blubber attached, is a delicacy. It is also an important source of vitamin C, which is hard to find in the Arctic Circle. By custom, one or two vertebrae from each animal become tools and art.

  An Inuit legend explains the tusk. A woman with a harpoon rope tied around her waist was dragged into the sea after the harpoon struck a large narwhal. She became a narwhal herself, and her hair, worn in a twisted knot, turned into the spiralling tusk.

  In Europe, a medieval belief held that narwhal tusks were the horns of the legendary unicorn. Tusks were thought to have magical properties, to counter poison, and to cure illnesses such as measles and rubella. They were worn on staffs and thrones, and the tusk appears in art such as The Lady and the Unicorn. Belief faded as modern science rose toward the end of the 17th century, and once the unicorn idea was refuted, tusks were rarely used for magic.

  Vikings and Greenland Norse likely began the trade, and tusks later travelled through European channels to the Middle East and East Asia. It is unclear whether the Norse hunted the whales or mainly collected tusks from animals killed by orcas. Tusks were state gifts to medieval kings and queens, and in the 18th and 19th centuries a tusk was said to cost a couple of hundred times its weight in gold. Ivan the Terrible had a jewellery-covered tusk on his deathbed. Elizabeth I received one, allegedly valued at £10,000, from the privateer Martin Frobisher. Both tusks became staples of cabinets of curiosities.

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• 8. Threats And Numbers

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  In 1914 and 1915, around 1,000 narwhal carcasses were found after entrapment events, mostly in places such as Disko Bay in West Greenland. Sea-ice entrapment happens when narwhals fail to leave before the Arctic freezes in late autumn. If open water vanishes and the ice is too thick to break, they drown, or starve. Breathing holes can lie up to 1,450 metres apart, and each must be at least 0.5 metres wide for an adult to breathe. Several entrapments in 2008-2010 struck places where none had been recorded, which suggests later departures from summering grounds.

  Polar bears have been recorded waiting at breathing holes for young narwhals. Orcas have been seen surrounding and killing whole pods. To escape orcas, narwhals may hide under ice floes by staying submerged for long periods rather than relying on speed. Disease is a further hazard. Researchers found Brucella bacteria in many narwhals during a 19-year study, and the whales also carry whale lice, Toxoplasma gondii, morbillivirus and papillomavirus. In 2018, a female narwhal was found with an alphaherpesvirus.

  About 1,000 narwhals are killed each year, 600 in Canada and 400 in Greenland. Canadian catches held steady in the 1970s, fell to 300-400 a year in the late 1980s and 1990s, and have risen since 1999. Greenland took 700-900 a year in the 1980s and 1990s. Hunters sell skin, meat, teeth, tusks and carved vertebrae, and an average of one to two vertebrae and teeth are sold per whale. In Greenland, muktuk goes commercially to fish factories, and in Canada to other communities. Hunts receive subsidies but continue mainly to support tradition. An economic analysis noted that whale watching could be another source of income.

  Heavy metals build up in narwhals as they grow, probably from ocean pollution. A study found the blubber nearly free of them, while the liver and kidneys held dense concentrations. Compared with the liver, the kidney held more zinc and cadmium, and far less lead, copper and mercury.

  Narwhals are among the Arctic marine mammals most vulnerable to climate change, especially in northern wintering grounds such as Baffin Bay and the Davis Strait. Satellite data show markedly less sea ice there than before. Narwhals tend to return to the same wintering areas even as conditions shift. In 2002, hunters in Siorapaluk caught more narwhals without working harder, which suggests climate change may be making the whales easier to hunt. Seismic surveys linked to oil exploration disrupt migration, and disturbed migrations may also raise the risk of entrapment.

  The International Union for Conservation of Nature lists the narwhal as a species of least concern. As of 2017, the global population was estimated at 170,000, including 123,000 mature individuals. Around 12,000 narwhals lived in northern Hudson Bay in 2011, and about 49,000 near Somerset Island in 2013. Estimates elsewhere include 17,000 in eastern Baffin Bay, 12,000 in Jones Sound, 16,000 in Smith Sound, 8,000 in Inglefield Bredning and 3,000 in Melville Bay. Roughly 800 narwhals live off Svalbard.

  The 1972 Marine Mammal Protection Act banned imports of narwhal products into the United States. The species sits on Appendix II of CITES and of the Convention on the Conservation of Migratory Species of Wild Animals, and Canada classes it as special concern under COSEWIC. In 2025, the United Kingdom protected narwhals under the Ivory Act, which forbids trade in teeth and tusks except for 'artistic and cultural artifacts.'

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