What is the narwhal's horn used for? Mating season and lifespan
The narwhal is called the “unicorn of the sea” because of a long “horn” protruding from the top of its head, but it is not actually a horn - it is a tooth, and it can reach 2.7 meters in length. What is the narwhal's horn used for? In which months does it mate? How long does it live?
A 2014 study published in the journal The Anatomical Record showed that the narwhal's tusk is a sensory organ that helps them sense changes in the external environment. Male narwhals can also use the tusk to find food and mates.
The researchers found that the outer cementum layer of the narwhal's tusk is porous, the inner dentin layer has some tiny tubes leading to the middle, and the pulp in the central part has nerve endings directly connected to the animal's brain. This structure makes the tusk very sensitive to temperature and chemical changes in the environment. For example, when the tusk was exposed to salt water of different concentrations, the researchers found that the narwhal's heart rate also changed. Narwhals can “taste” the concentration of chemicals in the water, so the researchers believe that male narwhals may use the tusk to find food, and they also seem able to use the tusk to find female narwhals and prepare to mate.
In addition to helping narwhals find food, the tusk can also be used to handle food. For example, a male narwhal will use its tusk to track cod, and when the tusk gets close enough to the cod, the narwhal uses it to stun the cod with a quick strike, then slowly enjoys the meal. These findings have already excited researchers enough, but they will continue to explore and discover more secrets about the narwhal's tusk.
In which months does the narwhal mate? How long does it live?
The narwhal is a seasonal breeder, with a gestation period of about 15.3 months. The mating season is from March to May, and calves are born between July and August of the following year. The duration of lactation is unknown, but it is guessed to be comparable to the beluga's 20-month lactation period. The interval between births is usually 3 years, with one calf per birth (there are also some records of twins). The calf leaves the mother's uterus tail first and head last. A newborn calf has a blubber layer up to 25 mm thick, a body length of 1.5 to 1.7 meters, and a weight of 80 kg. It can swim immediately after birth, but is still cared for by the female for some time. Both sexes usually reach sexual maturity at 4 to 7 years of age. At maturity, a female narwhal is 4 meters long and weighs 900 kg, while a male is 4.7 meters long and weighs 1600 kg. The wild lifespan is about 50 years, and captive breeding has not yet been successful.
Threats to narwhal populations
The narwhal's natural enemies include killer whales, walruses, polar bears and sharks, yet none of these compare to humans. Inuit people have hunted narwhals for their precious tusks and thick skin for centuries, and eating their skin raw is their traditional delicacy, while the meat is used to feed dogs, and the blubber and fat can be used for burning and lighting. At present, Inuit people in Canada hunt narwhals with high-speed motorboats and powerful rifles, causing unnecessary harm, because at least half of the wounded narwhals will sink or escape, but still cannot avoid death. Although the annual hunting quota is several hundred, the total number killed is often far higher than that.
Morphological characteristics of the narwhal
The narwhal's body length is generally 4 to 5 meters (not including the tusk), with males slightly longer than females. The average body weight of an adult whale is 800 to 1600 kg. It has no dorsal fin, and the way its neck and vertebrae connect is more like that of other mammals, unlike dolphins and whales. Its belly is white, and its back has many dark brown or black spots. At birth, the skin color is very dark, and as it ages, the skin becomes increasingly white. By sexual maturity, many white patches appear on the belly, and in older narwhals the body color is almost white again, so they may be confused with belugas.
Feeding habits of the narwhal
The narwhal is a deep diver and forages at various depths in the ocean. In winter it preys on benthic organisms, especially flounder living under thick ice. In summer its main food is Arctic cod, flounder and some other fish. The narwhal's feeding activity is irregular, and it surfaces for only very short periods. Dives usually last 7 to 20 minutes. When migrating, it swims very fast and floats at or near the sea surface. When hunting, it may circle or move slowly, and all members of the group may surface or dive at the same time. It may rest at the surface for as long as 10 minutes, exposing part of its back or one pectoral fin. In poor sea conditions, it tends to rest in deeper water.