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What is the use of the 2.7-meter-long narwhal?

author:A long way to go

For centuries, scientists have been fascinated by and puzzled by the narwhal, a whale native to the Arctic: this small whale has long spiral teeth that can reach 2.7 meters long! In the past, narwhal was regarded as the embodiment of the legendary unicorn, and some royal families even used whale teeth as a tool for exorcism and detoxification. Scientists know little about the use of this tusk of the narwhal. Recently, however, they have finally made a breakthrough in unravelling the mystery of the narwhal's 3-meter tusks.

Although it is called "narwhal", the long stick sticking out of its front is not a horn, but a tooth.

What is the use of the 2.7-meter-long narwhal?

Master diver

The weight of the narwhal reaches 1000 kg ~ 1600 kg, and the body length can reach 4 m ~ 4.5 m, which does not take into account its tusks.

As a protected Arctic species, narwhal is a social animal that lives mainly in the northern tip of the Atlantic Ocean and the Arctic Ocean, and a small number of narwhals are also found in the Greenland Sea. Inuit loved to hunt narwhals' tusks, flesh and skins. Scientists have long known that narwhal can dive about 900 meters in the sea at a near-vertical angle, and repeat this action many times a day, which is definitely a diving master.

What is the use of the 2.7-meter-long narwhal?

What exactly is the use of this marine mammal tusk? This question has puzzled scientists because, despite its name, teeth are incompatible with the principle of teeth in general. It is almost half the length of a narwhal and generally grows from the left side of the male narwhal's jaw and mouth. You can imagine what it would be like if a 2-meter-tall person had a 1-meter-long tooth.

In addition, unlike the curved teeth of elephants and warthogs, narwhals have inherently straight teeth. It has a spiral pattern on it, rotating to the left around the same axis. Scientists have speculated that this spiral tusk may minimize fractures, and previous studies have shown that this spiral helps narwhals grow straighter during their developmental stages.

Another unique feature of narwhal teeth is that they have gender. This tusk is common on male narwhals, but female narwhals do not have such tusks. Female narwhal teeth are also exposed, but short.

What is the use of the 2.7-meter-long narwhal?

Males are slightly longer than females. The average weight of adult whales is 800~1600 kg. Narwhal whales do not have dorsal fins, and their necks and vertebrae are connected more like other mammals than dolphins and whales. The belly is white with many dark brown or black spots on the back. Narwhal whales are born with dark skin, and as they age, their skin becomes whiter, and when they are sexually mature, many white patches appear on their abdomen, and the older narwhal is almost white in color, so it may be confused with beluga whales. The most striking feature of narwhals is the long tusks protruding from their heads, which are canine teeth protruding from the left upper jaw outside the lip, up to 2~3 meters in length, spiral-shaped, because they look like horns, hence the name. In addition to fighting, teeth are also a symbol of its status in the family, and the longer and thicker the narwhal's teeth, the higher its status in the whale group.

Narwhals are found mainly in the Atlantic and Arctic Oceans, with most concentrated in the bays and inlets of northern Canada and western Greenland. They are deep divers who forage at depths of the ocean, prey on benthic organisms in winter, especially halibut, which live under thick ice, and Arctic cod, flounder, and some other fish in summer.

Listed on the IUCN Red List of Threatened Species (IUCN) 2021 - Not Threatened (LC).

What is the use of the 2.7-meter-long narwhal?

Morphological characteristics

The narwhal has a small, rounded head with an inconspicuous beak and a protruding frontal that is slightly upturned in front of the mouth. The neck moves freely with a few marks of neck creases. The pectoral fins are dark grey , small , broad , but short in length , and the ends of the pectoral fins curve upwards (the ends curve upward with age). There is no dorsal fin , but there is a low fleshy bump on the back half of the back. The back and side of the body are mottled. The abdomen is pale or white in color. The central caudal fin is clearly absent; The anterior edge of the caudal fin becomes more concave with age, and the posterior margin protrudes outward with age.

The body color of narwhal varies significantly with age, with newborns appearing spotted grey or brownish-grey. 1 to 2 years old is uniform purplish-gray; White patches appear during puberty; Adult whales have black or dark brown patches on a gray background; The old whale is almost completely white.

Adult teeth have snow-white ends and are usually smoothly ground. Most of the teeth are hollow and fragile. Adult narwhals come in two tusk forms:

What is the use of the 2.7-meter-long narwhal?

Double teeth

The upper jaw has two teeth. When the male whale is one year old, the left tooth protrudes and becomes tusks; However, the male whale has a 2‰ chance of protruding both teeth, forming double tusks. Only a few people have ever seen "double-tusked narwhal" in the wild. Only one female whale has been found with double tusks. All male whales have tusks on the left side, the extra right tusk is usually shorter than the left one, and the spiral of both tusks is counterclockwise (as seen from the root).

Single teeth

The tusks pierce the upper lip in a counterclockwise spiral (as seen from the root). Almost all teeth come out of the teeth on the left side of the upper jaw, with an average length of 2 meters and a maximum length of 3 meters. The base of the teeth can reach a circumference of up to 30 cm and weigh up to 10 kg. About 3% of female whales develop a slender long horn, rarely exceeding 1.2 meters in length.

Size measurement: adult head to tail length 4~5 meters; Weight 800~1600kg. Male teeth are 150~267 cm long.

Habitat

Conventional wisdom holds that narwhals are deep-water whales, but in fact they feed at depths in layers of the ocean near the Arctic pack ice belt.

Life habits

The feeding action is irregular, the time to surface is extremely short, and the diving time is usually 7~20 minutes; When migrating, it swims extremely fast and floats on or near the surface of the sea; When hunting, it goes around in circles or moves slowly. All members of the group may float or dive at the same time. may rest for up to 10 minutes at sea, exposing part of the back or one pectoral fin; When the sea conditions are poor, they tend to stay in the depths to rest. Tusks may rise out of the water. Floating, whale tail striking waves, and pectoral fins slapping water are quite common. He rarely jumps to hit the waves, but occasionally sprints on the surface. The jet is weak and often inconspicuous.

What is the use of the 2.7-meter-long narwhal?

Male narwhals compete with each other with their tusks, either in the water or on the surface; The sound made was like two wooden sticks hitting each other. Young male whales often frolic and fight, but rarely poke each other; Older males are often scarred after fierce fights. There may be more than two narwhal fighting, sometimes a third (male or female) acting as an "observer". It is believed that fighting is used to establish the dominance of social classes and maintained through the ritual of tusk competition. The strongest males, who are also usually the longest and thickest with their tusks, may mate with more females.

Usually groups of 1~25 animals, there are hundreds or even thousands of animals traveling together. "Small groups" are made up of a mixture of animals, but they are generally segregated by age and sex. Females and larves often form flocks, while larves or males often form individual tissues. Hundreds of small groups may gather to swim together, and thousands of narwhal whales may spread over several square kilometers at this time; Gender segregation is most pronounced in large groups during autumn migration. When male whales float to the surface to breathe, tusks are occasionally seen, but generally below the surface; The social status of narwhal is related to the length of its tusks. Large flocks of male whales mostly stay far from shore than females or cubs.

Breeding methods

Narwhals are seasonal breeders. The gestation period is about 15.3 months, the mating season is in March ~ May, and the litter is born in July and August of the following year. The duration of lactation is unknown, but it is speculated to be comparable to the 20-month lactation period of Delphinapterus leucas. The interval between re-births is usually 3 years. Each litter gives birth to one litter (there are also some records of twins), the pup tail first heads and then leaves the womb of the mother whale, the newborn whale blubber layer is 25 mm thick, the body length is 1.5~1.7 meters, and the weight is 80 kg. It can swim after birth, but is still nursed by the female whale for a period of time. Both sexes are usually sexually mature at the age of 4~7, and the female whale in the mature stage is 4 meters long and weighs 900 kg; The male whale is 4.7 meters long and weighs 1600 kilograms.

Wild narwhals live about 50 years, and captive breeding has not been successful.

Population size

The global population size of narwhal is more than 80,000. Populations in the Canadian Arctic Highlands contribute the most to global populations, estimated at over 70,000 head (Innes et al. 2002; NAMMCO/JCNB 2005)。 In addition, thousands of narwhal may roam bays and fjords along the east coast of Baffin Island during the summer (NAMMCO/JCNB 2005). ABOUT 3500 NARWHAL WHALES FLOCK IN THE NORTHERN HUDSON BAY (COSEWIC 2004). West Greenland (Inglefield and Melville Bay) has more than 2,000 individuals clustered in the summer of two years; East Greenland is roughly estimated to be more than 1,000; The wintering colony in Central Greenland in 1998 and 1999 was about 2800 individuals (Heide-Jørgensen & Acquarone 2002).

Population threat

Narwhal's natural predators include killer whales, walruses, polar bears and sharks; However, these are not comparable to humans. Eskimos have hunted narwhal for centuries for its valuable tusks and thick skin; Eating raw skin is their traditional delicacy; Meat is used to feed dogs, and blubber and fat are used for burning and lighting. At present, the Inuit in Canada hunt narwhals with high-speed locomotive boats and powerful rifles, causing unnecessary injuries, because at least half of the injured narwhals will sink or escape, but it is still difficult to escape; Although the annual quota is in the hundreds of kills, the total number of killings is often much higher.

Narwhal is not thought to be in danger of extinction. Even so, the Convention on International Trade in Endangered Species of Wild Fauna and Flora lists narwhals in the trade to monitor and regulate their tusks to put the species at risk of extinction.

What is the use of the 2.7-meter-long narwhal?

Main value

Since narwhal's tusks are reminiscent of unicorn legends, for centuries it was believed to have medicinal effects and even magical powers. In the Middle Ages, when tusks were most valuable, "unicorn horns" cost ten times as much as gold of the same weight. Legend has it that Queen Elizabeth of England received a tusk worth £10,000, which could have bought a castle at the time.

Related research

Most climate research uses weather balloons, satellites, deep-sea and ice drilling equipment to obtain data on global climate change. Biologists at the University of Washington have taken a new approach: They attach sensing devices to the back of a narwhal and rely on its activity to obtain information. Kristin Laidre and her colleagues at the Applied Physics Laboratory at the University of Washington's Polar Science Center equipped three narwhals with satellite transmission equipment and tracked their movements to measure water temperatures in an area. The three narwhals tracked by the scientists were all caught in the summer of 2006. Each whale transmits more than 400 temperature data per day. In the second phase of work, which has been completed, physicists have also obtained additional data, including salinity, through detection instruments installed in the depths of the ocean.

The function of teething

The male narwhal is often unique and cannot be confused with other whales. Spiral teeth are actually vestigial teeth, much like rough and spiraled crutches; Until the early 17th century, narwhal tusks were still regarded as the horns of legendary unicorns. Over the years, the function of this tooth has puzzled many scientists. Among the many theories, some believe that it can be used to spear fish, dig for food or gouge through ice. It is true that narwhals are often trapped by rapidly freezing ice, but instead of using tusks, they use their heads to make the breathing holes they need. The function of tusks may also be similar to the pronghorns of a deer, a tool for competing hearts and showing strength; On average, about 1/3 of male whales have tusks that break; Most old male whales also have scars on their heads. Most females do not have tusks.

Other studies have found that narwhal tusks have many neural channels on the surface, speculating that the tusks may be a tool for male narwhals to test water temperature and air pressure. Ryder and Hyde Jesson point out that female narwhals without tusks live longer, so tusks are not critical to narwhal survival.

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