Facts About Narwhals, the Unicorns of the Sea

Unicorns Really Do Exist

The narwhal's unicorn horn is actually special type of tooth.
The narwhal's unicorn horn is actually special type of tooth. Dave Fleetham / Design Pics / Getty Images

The narwhal or narwhale (Monodon monocerus) is a medium-sized toothed whale or odontocete, best known for its long spiral tusk that many people associate with the unicorn myth. The tusk is not a horn, but a protruding canine tooth. The narwhal and the only other living member of the Monodontidae family, the beluga whale, live in the world's arctic waters.

Carl Linnaeus described the narwhal in his 1758 catalog Systema Naturae.

The name narwhal comes from the Norse word nar, which means corpse, combined with whal, for whale. This common name refers to the mottled gray-over-white color of the whale, which causes it to somewhat resemble a drowned corpse. The scientific name Monodon monocerus comes from the Greek phrase meaning "one tooth one horn".

The Unicorn Horn

A male narwhal has a single long tusk. The tusk is a hollow left-handed spiral helix that grows from the left side of the upper jaw and through the whale's lip. The tusk grows throughout the whale's life, reaching a length from 1.5 to 3.1 m (4.9 to 10.2 ft) and weight of approximately 10 kg (22 lb). About 1 in 500 males has two tusks, with the other tusk formed from the right canine tooth. Around 15% of females have a tusk. Female tusks are smaller than those of males and not as spiralized. There is one recorded case of a female having two tusks.

Initially, scientists speculated the male tusk might be involved in male sparring behavior, but the current hypothesis is that tusks are rubbed together to communicate information about the ocean environment.

The tusk is rich with patent nerve endings, allowing the whale to perceive information about the seawater.

The whale's other teeth are vestigial, making the whale essentially toothless. It is considered a toothed whale because it does not have baleen plates.

Description

The narwhal and beluga are the "white whales".

Both are medium-size, with a length from 3.9 to 5.5 m (13 to 18 ft), not counting the male's tusk. Males are typically slightly larger than females. Body weight ranges from 800 to 1600 kg (1760 to 3530 lb). Females become sexually mature between 5 and 8 years of age, while males mature at around 11 to 13 years of age.

The whale has mottled gray or brown-black pigmentation over white. Whales are dark when born, becoming lighter with age. Old adult males may be almost entirely white. Narwhals lack a dorsal fin, possibly to aid in swimming under ice. Unlike most whales, the neck vertebrae of narwhals are jointed like those of terrestrial mammals. Female narwhals have swept-back tail fluke edges. The tail flukes of males are not swept back, possibly to compensate for the drag of the tusk.

Behavior

Narwhals are found in pods of five to ten whales. The groups may consist of mixed ages and sexes, only adult males (bulls), only females and young, or only juveniles. In the summer, large groups form with 500 to 1000 whales. The whales are found in the Arctic ocean. Narwhals migrate seasonally. In the summer, they frequent coastal waters, while in the winter, they move to deeper water under pack ice.

They can dive to extreme depths -- up to 1500 m (4920 ft) -- and stay under water about 25 minutes.

Adult narwhals mate in April or May offshore. Calves are born in June or August of the following year (14 months gestation). A female bears a single calf, which is about 1.6 m (5.2) feet in length. Calves start out life with a thin blubber layer that thickens during lactation of the mother's fat-rich milk. Calves nurse for about 20 months, during which time they remain very close to their mothers.

Narwhals are predators that eat cuttlefish, cod, Greenland halibut, shrimp, and armhook squid. Occasionally, other fish are eaten, as are rocks. It is believed rocks are ingested by accident when whales feed near the bottom of the ocean.

Narwhals and most other toothed whales navigate and hunt using clicks, knocks, and whistles.

Click trains are used for echo location. The whales sometimes trumpet or make squeaking sounds.

Lifespan and Conservation Status

Narwhals can live up to 50 years. They may die from hunting, starvation, or suffocation under frozen sea ice. While most predation is by humans, narwhals are also hunted by polar bears, walruses, killer whales, and Greenland sharks. Narwhals hide under ice or stay submerged for long periods of time to escape predators, rather than flee. At present, about 75,000 narwhals exist worldwide. The International Union for Conservation of Nature (IUCN) classifies them as "Near Threatened". Legal subsistence hunting continues in Greenland and by the Inuit people in Canada.

References

Linnaeus, C (1758). Systema naturae per regna tria naturae, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio decima, reformata. Holmiae. (Laurentii Salvii). p. 824.

Nweeia, Martin T.; Eichmiller, Frederick C.; Hauschka, Peter V.; Tyler, Ethan; Mead, James G.; Potter, Charles W.; Angnatsiak, David P.; Richard, Pierre R.; et al. (2012). "Vestigial tooth anatomy and tusk nomenclature for Monodon monoceros". The Anatomical Record. 295 (6): 1006–16.

Nweeia MT, et al. (2014). "Sensory ability in the narwhal tooth organ system". The Anatomical Record. 297 (4): 599–617.