Known as the unicorn of the sea, a narwhal is a medium-sized whale with a distinguishable horn protruding from its head. The horn is actually it's overgrown canine tooth that acts as a defensive organ. The pointed canine teeth grow throughout the entire life. Only 15% of the females grow such canine tusks. The closest relative of a narwhal is the beluga whale. They are almost similar in morphological features except for the tusk and skin textures. This whale species exists in the arctic waters of Greenland, Russia, and Canada. It is also one of the two Monodontidae species of whale. The other one is the beluga whale. This species was one of the described animals found in the Systema Naturae written by Carl Linnaeus, the father of taxonomy and classification. Keep on reading to find interesting facts about this species.
What is a Narwhal?
The scientific name of this medium-sized whale is Monodon monoceros. This is one of the species included in the family Monodontidae. This whale can be easily recognized by its characteristic canine tusk. The tusk is helical and emerges from the left canine location of its mouth. It can be found in the cold Arctic water of Canada, Greenland, and Russia throughout the year. This mammal is carnivorous and feeds on the squids, cod, halibut, small fish, etc. They like to stay forming a colony or a pod. Only 15% of the females develop a canine tusk, like all the males. This canine tusk grows throughout the entire lifespan of this species.
A narwhale is an exceptional marine mammal that lives in the coldest regions and has a tusk developed from its upper left canine. Two tusked narwhal whales are quite rare. The skulls of two-tusked narwhal males are evidence of this rare biological phenomenon. This is one of the species that Carl Linnaeus, the father of taxonomy, has described in his book Systema Naturae published in the year 1758. Sailors from different parts of the world have witnessed this marine unicorn and have mentioned it in their fables and stories.
About Narwhal: Taxonomy
The name ‘narwhal’ emerged from the word ‘nár’, an old Norse word that depicts a dead body or corpse. It was suggested by the then sailors due to its grayish spotted pigmentation. In fact, this animal floats on the water without making any movement resembling a grayish corpse of a sailor. This is how the name emerged from the old observations done by the sailors in the Arctic Ocean. The characteristic pigmentation of the narwhal whale varies considering its age and life stage. Its scientific name Monodon monoceros means one tooth, one horn in Greek. You will be astonished to know that this is one of the two species included in the Monodontidae Family. The other one is the beluga whale.
A narwhal is a medium-sized whale with a length of 4 m with no true dorsal fin. They have short and round snouts that distinguish them from dolphins. The head is round, consisting of round sensory organs. Despite being from different genera, the beluga whale and narwhal may rarely interbreed. An anomalous whale skull was discovered in the western part of Greenland that showed consistent features midway between a beluga whale and a narwhal whale. After proper isotropic and DNA analyses, it was confirmed that this skull belongs to a hybrid whale that was an offspring of a narwhal and a beluga whale.
It has also been found that these medium-sized white whales used to live in tropical waters 11 million years ago. Due to the shortage and transformation of the food chain, they shifted from the tropical marine ecosystem to the Arctic ecosystem. It happened during the Pliocene era.
The morphological features tell us more about narwhals. This mammal is an exception from almost all the marine animals we know due to its exclusive canine tusk. It is a medium-sized whale with a length ranging from 3.95 m to 5.5 m. The average length of a male narwhal is 4.1 m or 13.5 feet. The males are slightly bigger in size than the females. Apart from the tusk, every external morphological feature is the same. The average body weight of the narwhals ranges from 800 to 1600 kg. The male whales attain puberty at the age of 11-13 years. The females attain sexual maturity at an early stage when they are 5-8 years old. During their maturity, the males attain a length of 3.9 m whereas the females attain a length of 3.4 m.
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As described before, the narwhal meaning comes from a dead grayish corpse of a sailor. It is because of its spotted grayish fur that gives its name. The mottling pattern on the skin comes from blackish-brown spots on a grayish-white background. This grayish tinge of their skin is darker when young. It becomes white as the whale grows older. The body also has white patches in the navel region. In fact, the genital slit also develops such patches during puberty. The older males are almost white in color.
The dorsal fin in this species is not visible, unlike the dolphins. It is considered to be an evolutionary adaptation as this species has to swim under the ice and catch fish. The disappearance of the dorsal fin also suggests that this species can easily roll, get closer to the undersurface of ice, and loses less heat than other animals. They also have a shallow dorsal ridge. In fact, they can also turn their heads like other land mammals. Most other whales have fused neck vertebrae that do not allow them to turn their heads. This is what makes the narwhal animal different from other whales. Female narwhals live longer than males. The tusk is also a sexual trait similar to that of the antlers and manes of other mammals on land.
About Narwhal Tusk
The most significant part of this animal’s morphology is its tusk. As mentioned earlier, a narwhal can be easily identified by its canine tusk. A single long helical tusk can be seen originating from the mouth. On closer observation, the tusk is nothing but the extension of the left upper canine tooth. Every male narwhal has a tusk. It is rare to find double tusks originating from both the upper canines. The tusk forms a left helical spiral and it grows throughout the entire life span. The length can reach up to a considerable length. It can range between 1.5 m and 3.1 m. The tusk is hollow and can be 10 kg in weight. It has been documented that one out of 500 males can grow two tusks. Only 15% of the female narwhals can grow tusks. The female tusks are smaller than the male ones with fewer spiraling features.
Scientists are baffled and clueless regarding the functions of the male tusks. They are unable to find a solid ground that can theorize the biological implication of the narwhal tusk. The only theory that has been accepted worldwide without any significant information is that the tusk is a secondary sexual characteristic. It has also been hypothesized that a tusk is used as an assessment tool for the hierarchical status of the males in a pod. On the other hand, the physiological analysis suggests that a tusk has millions of nerve endings. It can also act as a sensory organ for these whales living in cold Arctic water. It can also be used as an appendage collecting information from the oceanic water.
It has also been found that male narwhales often rub their tusks with each other. This can also be a method of communication adopted by these whales. They might be able to pass information about the water they have scouted. Sharing information helps the whales to survive in this dangerous ecosystem. It was previously thought that males rival each other by locking their tusks to show superiority and masculinity. Documentation suggests that these tusks are also used to tap on water and to stun Arctic cod. A tusk is surrounded by vestigial teeth. These teeth appear laterally, ventrally, and posteriorly and protrude from the individual tooth sockets. These teeth can be seen surrounding the tusk at the base. Hence, the mouth of the narwhal whales is toothless.
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Distribution of the Narwhales
As mentioned earlier, these whales have shifted from their tropical oceanic habitat to the Arctic cold oceanic habitat millions of years ago. They are predominantly found in pods roaming in the water of the Atlantic Ocean and the Arctic Ocean surrounded by Russia, Greenland, and Canada. The Canadian archipelago in the Arctic region comprises the northern part of Hudson Strait, Hudson Bay, and the Baffin Bay. It includes the eastern coast of Greenland. This is the natural habitat of narwhales.
Social Behavior of Narwhales
They are social animals and tend to exist in a pod of 5-10 members. The groups can be nurseries comprising females, young ones, and post-dispersal adult males. During the winter season, the group can also increase to 20. A fascinating phenomenon is observed during the summertime. As many as 500-1000 narwhales emerge and become a single pod. It is during this time, the male narwhals practice tusking. They rub their tusks with other males to either communicate. This helps them to exchange information regarding the water condition and other features of the oceanic ecosystem.
They also show excellent migratory behavior. They will return to the summer grounds from where they left. The ice-free grounds during the summer season are ideal for catching fish and mating. They also prefer going to the shallow water near the coastal regions. During the winter season, they will move to deeper water away from the shore where the ice is thicker and denser. The narrow fissures help them to come to the surface to breathe. These fissures open up during the spring forming channels for returning to the coastal regions.
Female narwhals start breeding when they are 6-8 years old. The gestation period spans 14 months. The calves are born during the months of June-August. A single calf is given birth by a female whale. A newborn calf is 1.6 meters in length.
Narwhal feeds on the Arctic and polar cod, Greenland Halibut, shrimps, squid, and cuttlefish. The feeding mechanism of these whales is a little different from that of the rest of the family. They go close to the prey and then suddenly open their mouths to suck it in. The tusks might not let them charge to their prey or injure them. Due to a lack of proper dentition, they cannot catch or bite on the prey. The only way to get hold of the prey is to get very close to them and open to their mouth. It requires high motility and flexibility. They use their tusks to tap on water and stun the prey and then quickly get close to eat them. Narwhals wait for the summer season when the fish population is high. They wait for the entire year and go feeding intensely during this season.