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What is Narwhal? Characteristics and Curiosities

El narval es un mamífero marino caracterizado por un cuerno.

The narwhal (Monodon monoceros) is a medium-sized toothed whale with a large protruding canine tooth “tusk”. It lives year-round in the Arctic waters surrounding Greenland, Canada and Russia. It is one of two living species of whales in the family Monodontidae, along with the beluga whale. Male narwhal are distinguished by a long, straight, helical tusk, which is an elongated upper left canine

The narwhal was one of many species described by Carl Linnaeus in his publication Systema Naturae in 1758.

Narwhals are medium-sized whales and are about the same size as beluga whales. Total length in both sexes, excluding the male’s tusk, can range from 3.95 to 5.5 m (10 to 15 ft). Males, with an average length of 4.1 m, are slightly larger than females, with an average length of 3.5 m

Typical adult body weight ranges from 800 to 1,600 kg (1,760 to 3,530 lb). Male narwhals reach sexual maturity between 11 and 13 years of age, when they are about 3.9 m (12.8 ft) long. Females reach sexual maturity at an earlier age, between 5 and 8 years, when they are about 3.4 m (12.8 ft).

The pigmentation of narwhals is a mottled pattern, with blackish-brown markings on a white background. They are darker at birth and become whiter with age; at sexual maturity white spots develop on the umbilicus and genital slit

Older males may be almost pure white. Narwhals do not have a dorsal fin, possibly an evolutionary adaptation to swim easily under ice to facilitate rolling or to reduce surface area and heat loss. Instead, narwhals possess a shallower dorsal crest

Their neck vertebrae are jointed, like those of land mammals, rather than fused as in most whales, allowing for great neck flexibility. The tail flukes of females have backward-swept leading edges and those of males have more concave leading edges and no backward sweep. This is thought to be an adaptation to reduce drag caused by the tusk.

Narwhals may live an average of 50 years, however, research suggests that narwhals may live as long as 115 ± 10 years and 84 ± 9 years for females and males, respectively

Mortality usually occurs when narwhals suffocate after failing to emerge before the surface of Arctic waters freezes in late autumn. Because narwhals need to breathe, they drown if the open water is no longer accessible and the ice is too thick for them to get through

Entrapment can affect up to 600 individuals, most of which occur in narwhal wintering grounds, such as Disko Bay. In the largest entrapment in 1915 in West Greenland, more than 1,000 narwhals were trapped under the ice.

The narwhal horn

El cuerno del narval.

The most conspicuous feature of the male narwhal is a single long tusk, which is actually a canine tooth that projects from the left side of the upper jaw, across the lip and forms a helical spiral to the left

The tusk grows throughout life, reaching a length of between 1.5 and 3.1 m. It is hollow and weighs about 10 kg. It is hollow and weighs about 10 kg (22 lb). Approximately one in 500 males has two tusks, which occurs when the right canine also grows through the lip. Only about 15 percent of females have one tusk, which is usually smaller than that of males, with a less noticeable spiral. Collected in 1684, only one case is known of a female growing a second tusk.

Scientists have long speculated about the biological function of the tusk. Proposed functions include use of the tusk as a weapon, to open breathing holes in sea ice, in feeding, as an acoustic organ, and as a secondary sexual character.

The leading theory has long been that the narwhal tusk serves as a secondary sexual character of males, for nonviolent evaluation of hierarchical status on the basis of relative tusk size. However, detailed analysis reveals that the tusk is a highly innervated sensory organ with millions of nerve endings that connect stimuli from seawater in the external ocean environment to the brain

The rubbing of tusks by male narwhals is believed to be a method of communicating information about the characteristics of the water each has passed through, rather than the previously assumed posture display of aggressive rivalry between males

In August 2016, drone videos of narwhal surface feeding in Tremblay Sound, Nunavut, showed that the tusk was used to strike and stun small Arctic cod, making them easier to capture for food. The tusk may not serve a critical function for the survival of the animal, as females – which generally do not have tusks – tend to live longer than males. Therefore, the general scientific consensus is that the narwhal’s tusk is a sexual trait, just like a deer’s antlers, a lion’s mane or a peacock‘s feathers.

El hábitat del narval.

The narwhal is predominantly found in the Atlantic and Russian areas of the Arctic Ocean. Individuals are commonly recorded in the Canadian Arctic archipelago, such as in northern Hudson Bay, Hudson Strait, and Baffin Bay; off the east coast of Greenland; and in a band running eastward from the northern tip of Greenland to eastern Russia.

The lands in this strip include Svalbard, Franz Josef Land, and Severnaya Zemlya. The northernmost narwhal sightings have occurred north of Franz Josef Land.

Hábitos y comportamientos del narval.

Narwhals usually gather in groups of five to ten, and sometimes up to 20 individuals outside of summer

Groups may be “nurseries” with only females and young, or may contain only postdispersed juveniles or adult males (“bulls”), but mixed groups may occur at any time of the year. In the summer, several groups come together, forming larger aggregations that may contain from 500 to more than 1000 individuals.

At times, a male narwhal may rub his tusk with another male, a display known as “tusking” and believed to maintain social dominance hierarchies. However, this behavior may show the use of the tusk as a sensory and communication organ to share information about water chemistry detected in the microchannels of the tusk.

Narwhals exhibit seasonal migrations, with high return fidelity to preferred, ice-free summering areas, usually in shallow water

In the summer months, they approach the coasts, often in groups of 10 to 100 individuals. In winter, they move into deeper water under the thick ice cover, surfacing in narrow fissures in the sea ice. Come spring, these fissures open into channels and the narwhals return to the coastal bays

Narwhal in Canada and western Greenland regularly overwinter in the pack ice of Davis Strait and Baffin Bay along the continental slope with less than 5% open water and high densities of Pacific halibut. Winter feeding accounts for a much larger portion of narwhal energy intake than in summer.

Like most toothed whales, narwhals use sound to navigate and hunt for food.

Narwhals vocalize primarily by “clicks,” “whistles,” and “blows,” created by the movement of air between chambers near the blowhole

These sounds are reflected from the sloping front of the skull and are focused by the animal’s melon, which can be controlled by musculature

Echolocation clicks are produced primarily for prey detection and obstacle location at close range. It is possible that individual “clicks” are capable of disorienting or disabling prey, facilitating hunting, but this has not been verified. They also emit tonal signals, such as whistles and pulsed calls, which are thought to have a communication function

Recorded calls from the same herd are more similar than calls from different herds, suggesting the possibility of group-specific or individual calls in narwhals. Narwhals can also adjust the duration and pitch of their pulsed calls to maximize sound propagation in varying acoustic environments.

Other sounds produced by narwhals include trumpet sounds and door squeaks. The vocal repertoire of narwhals is similar to that of closely related beluga whales, with comparable whistle frequency ranges, whistle duration, and repetition rates of pulsed calls, however beluga whistles may have a higher frequency range and more diversified whistle contours.

Narwhals have a relatively restricted and specialized diet. Their prey consists primarily of Pacific halibut, polar and arctic cod, cuttlefish, shrimp, and hook squid. Other items found in the stomachs have included wolf fish, capelin, skate eggs and sometimes rocks, accidentally ingested when the whales feed near the bottom.

Because of the lack of a well-developed dentition in the mouth, narwhals are believed to feed by swimming towards prey until it is close and then sucking it with considerable force into the mouth. The distinctive tusk is used to strike and stun small prey, making it easier to capture.

El oso polar es el principal depredador del Narval.

The main predators are polar bears, which attack in the breathing holes, mainly young narwhal, and Greenland sharks

Killer whales aggregate to overwhelm herds of narwhal in the shallow waters of enclosed bays, in one case killing dozens of narwhal in a single attack. To escape predators such as killer whales, narwhals may use prolonged submergence to hide under ice floes rather than relying on their own speed.

Humans hunt narwhal, often commercially selling the skin, carved vertebrae, teeth and tusk, while eating the meat, or feeding it to dogs. About 1,000 narwhal are killed annually, 600 in Canada and 400 in Greenland. Canadian catches remained at this level in the 1970s, declined to 300-400 per year in the late 1980s and 1990s, and increased again since 1999. Greenland harvested more, 700-900 per year, in the 1980s and 1990s.

Tusks are sold carved and uncarved in Canada and Greenland. An average of one or two vertebrae and one or two teeth per narwhal are carved and sold. In Greenland the skin (muktuk) is sold commercially to fish factories, and in Canada to other communities

Narwhals are one of many mammals threatened by human actions. Estimates of the global narwhal population range from about 50,000 (from 1996) to about 170,000 (compilation of various subpopulation estimates from the years 2000-2017).

They are considered to be nearly threatened and several subpopulations show signs of decline. In an effort to support conservation, the European Union established a ban on tusk imports in 2004 and lifted it in 2010. The United States has banned imports since 1972 under the Marine Mammal Protection Act. Narwhals are difficult to keep in captivity.

Alejandra Roig

Alejandra Roig

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