Narwhals are the unicorns of the ocean. The only species of whale with a horn, male narwhals grow a long, spiraled tooth as they mature. These mythic creatures live in the frigid waters of the Arctic in large groups.
What can we learn about these mysterious creatures? Are they really as untouchable as they seem? Let’s find out more.
1. Narwhal tusks are an enigma even to scientists
Narwhal tusks can grow up to three meters long and weigh ten kilograms. They have tiny holes that allow seawater into them, and they have nerves that could increase the sensitivity of the tusks. Some narwhals grow two tusks, while some female narwhals also grow smaller tusks. It is not known what affects tusk growth.
Scientists suggest that narwhal tusks are used to detect environmental changes, which could help them find prey or evade predators. Some scientists also believe that narwhal tusks are used for mating purposes, for example to impress female narwhals or to fight other male narwhals.
2. Narwhal tusks are the only straight tusks in the world
All other animal tusks curve, like elephants and walruses. The narwhal tusk grows straight but it forms a left-turning helix spiral, even when two tusks grow on the same narwhal. Narwhals usually grow their tusk from their upper left canine tooth, and their tusks can bend about a foot before they break.
Narwhal tusks are teeth, but their composition is inverted – the nerves of the tusk grow on the outside and the dense enamel, dentin and cementum coating is on the inside of the tusk. The tusk is hollow and scientists suggest that the presence of nerves on narwhal tusks mean that they are used as a sensory organ.
When a narwhal is swimming, sea water enters the tusk through tiny holes that direct the water to the base of the tusk, where the sensory centre is located. The sensory centre sends information like salt levels, water pressure, temperatures and chemical cues to the narwhal’s brain.
3. Narwhals are related to belugas
They are also related to porpoises, bottlenose dolphins and orcas. Like belugas, narwhals do not have a dorsal fin – this allows them to make breathing holes in sea ice. Narwhals can dive for up to 25 minutes to depths of more than 1800 meters, making them one of the deepest diving marine mammals. However, they spend most of their time at depths of 500 meters hunting fish and socializing.
4. Narwhals have no teeth besides the ones that turn into tusks
Narwhals are suction feeders, meaning that they swallow their prey whole. They eat squid, shrimp and fish, doing their hunting at the edges of ice and at the bottom of the sea. Their tusks can be used to stun their prey by tapping them, but they have no other teeth in their mouths for chewing or biting as it would be difficult to chew or bite prey with their long tusks.
Narwhals feed mostly in the winter months and eat less during the summer months, which is quite different from other whales that hibernate or eat less in the winter and travel to feed in the summer. Scientists suggest that this could be an evolved adaptation to prevent competition with other lower latitude whales for food.
5. Narwhals are Arctic creatures
They don’t migrate, instead spending the entirety of their lives in the frigid waters near Canada, Norway, Russia and Greenland. Narwhals travel in groups of 15 to 20 at a time, but they have also been seen gathering in the hundreds and thousands.
Narwhals are hunted by killer whales, polar bears and walruses. Inuit hunt narwhals for their ivory tusks and skin, which is a valuable source of Vitamin C in the Arctic. Sometimes, narwhals and beluga whales get trapped in pack ice when it shifts to shut them in a pool of open water. They either die as ice closes the hole or they fall prey to Inuit hunters and other animal predators.
6. Narwhals live for more than a century and they experience menopause
Newborn narwhal calves are blue-grey and start their lives at 1.6 metres long. They are weaned from their mother after a year and become sexually mature at six years old for females, while for males they become adult narwhals at eight. Juvenile narwhals are blue-black and adult narwhals are mottled grey. Adult narwhals weigh up to 1.5 tonnes and males can grow up to five metres long.
As they get older, their skin changes to become nearly all white. Older female narwhals go through menopause and they live a long time after they stop being able to reproduce. Narwhals can live up to 125 years old.
7. Narwhals are difficult to study, but they face significant threats from humans
The International Union for Conservation of Nature has listed narwhals as near threatened on their Red List. Because narwhals live so deep in the Arctic, they are difficult to access and observe – they live far away from humans in a habitat that is covered in ice and dark for at least half the year. Narwhals also do not do well in captivity, all attempts at capturing and keeping narwhals have failed as they die within several months. All narwhals kept in captivity have died, making it difficult for scientists to conduct research on behaviour.
Narwhals are directly affected by climate change because they depend on sea ice to live. The melting sea ice changes their prey’s living habits and increases their chances of being killed by killer whales. Melting sea ice results in unpredictable ice conditions, increasing their chances of being trapped in shifting ice. Narwhals are also affected by oil and gas development, as they often collide with shipping vessels. The noise generated from oil and gas development activities also creates noise pollution that makes it difficult for narwhals to communicate.
Narwhals get their name from their mottled skin – in Old Norse, “nar” means corpse and “hval” means whale.