The narwhal, "unicorn of the ocean," is amongst the world's rarest whales. They are very mysterious and elusive by nature, and their big horn-like tusk gives them a very distinctive appearance. The tusk is, in fact, a tooth that grows out of the male's upper jaw. Adult narwhals typically have black and white spots on the dorsal parts of their body, and older narwhals can be almost entirely white. Calves are typically a blotchy gray.
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Narwhals are scattered throughout Arctic waters and the North Atlantic Ocean. Most of them are found in Greenland and the eastern part of the Canadian Arctic Ocean. Narwhals migrate seasonally, with high fidelity of return to preferred, ice-free summering grounds, usually in shallow waters. In the summer months, they move closer to coasts, often in pods of 10-100. In the winter, they move to offshore, deeper waters under thick pack ice, surfacing in narrow fissures in the sea ice, or leads. As spring comes, these leads open up into channels and the narwhals return to the coastal bays.
Narwhals are gregarious and commonly occur in pods of between 6 and 20 animals, though most groups number between 3 and 8. These groups often are segregated by sex, and pods of male 'bachelors' are common. In the summer, several groups come together, forming larger aggregations that can contain from 500 to over 1000 individuals. At times, a bull narwhal may rub its tusk with another bull, a display known as "tusking" and thought to maintain social dominance hierarchies. Narwhals remain near pack ice for the whole year. Breathing holes are created through sheets of ice with thrusts of their thick head, sometimes by several of them at the same time. Due to the lack of well-developed dentition in the mouth, narwhals are believed to feed by swimming towards prey until it is within close range and then sucking it with considerable force into the mouth. The distinctive tusk is used to tap and stun small prey, facilitating a catch. Narwhals are very vocal, squeaking and clicking as they travel. Like many cetaceans, narwhals slap their flippers on the water as they surface, raising their tusks and heads out of the water.
Narwhals are polygynous, an adult male mating with multiple females during one mating season. Mating usually occurs from March to May, when males court the females and compete with one another. The gestation period is around 15 months, with calves being born in July and August the year following. Narwhals give birth to a single calf and they are born tail first. The tusks of males do not grow until they are weaned when they are about one year old. Young narwhals can swim soon after birth. A female will give birth once every three years. Males generally are reproductively mature between the ages of 8 and 10, while females achieve maturity when they are 4-7 years old.
Narwhals are hunted for meat, their skin, called "maktaq", and their ivory tusks, sold as curios or for carving. They are susceptible to climate fluctuations as well as long-term climate change. Their range declines as pack ice recedes. They have sometimes been trapped under the ice which forms too quickly for them to make a breathing hole. Industrial extraction, marine construction, shipping, and military activities cause noise pollution under the water. As narwhals depend on sound for communication, interference by noise pollution may impact their ability to navigate, access food and mates, avoid predators and look after their young.
According to the IUCN Red List, the global narwhal population size is around 80,000 individuals, including estimates for this species in specific regions: Canadian High Arctic - 70,000 animals; northern Hudson Bay - 3,500 animals; West Greenland - over 2,000 animals; East Greenland – fewer than 1,000 animals. The narwhal population is currently classified as Near Threatened (NT) on the IUCN Red List.
Narwhals are at the top of the food chain and have an important role in the overall health of the marine environment, controlling the populations of the prey items they consume.