Imagine seeing a whale rise from dark Arctic water with a giant spiral tusk pointing from its head. It looks almost like an animal from a storybook, yet the narwhal is very real. Often called the unicorn of the sea, this unusual whale spends its life in some of the coldest waters on Earth. Its famous tusks are not horns. It is actually an enormous tooth that can grow nearly 10 feet long.
Even more surprisingly, research shows that the tusk can sense changes in the surrounding water. From deep dives to life beneath Arctic ice, the narwhal has developed a remarkable set of features for surviving in a difficult environment.
The narwhal lives in the Arctic Ocean
Narwhals live in the Arctic Ocean, mainly across its Atlantic side. Their range stretches through waters around central Canada and Greenland toward eastern Russia. They spend much of their lives in places that are difficult for people to reach and study. During winter, narwhals can live among thick pack ice, using cracks and openings in the ice to reach the surface and breathe.
Their movements change with the seasons. Narwhals move from pack ice during winter toward inshore waters during spring. They spend more time around coastal waters during summer and move toward more open water during fall. Sea ice, therefore, plays an important role in their yearly movements. The difficult conditions also help explain why scientists still have questions about narwhal behavior. Following whales across remote Arctic waters and thick winter ice is far harder than watching animals living close to populated coastlines.
The famous narwhal tusk is really a tooth
The feature that made the narwhal famous is not technically a horn. Narwhals have two teeth in their upper jaw. In most females, these teeth remain inside the jaw. In males, however, the left tooth usually begins growing forward when the animal is around 2 or 3 years old. It eventually extends through the front of the jaw and upper lip to form the long tusk.
The tusk has a clear spiral and can grow to about 9.8 feet long. It can also weigh more than 20 pounds. The normal pattern is one tusk on a male, but nature does not always follow that arrangement. Females with tusks have been documented. Some males do not develop an erupted tusk, while rare males can develop two.
The tusk can sense the surrounding water
One of the most remarkable discoveries about the narwhal tusk involves its sensory abilities. A 2014 study examined the anatomy of the tooth and found evidence of a pathway that can carry information from the outside environment through the tusk and toward the whale’s brain.
The outside of the tusk contains tiny channels that connect with networks of microscopic tubules. The Smithsonian estimates that around 10 million of these fluid-filled tubules extend across the tusk. Unlike a normal human tooth protected by enamel, this unusual structure provides a connection between the ocean and the sensory system inside the tooth.
Scientists think the tusk has several jobs
For years, people have offered different explanations for why narwhals have such an enormous tooth. Scientists now have evidence that there may not be one simple answer. The tusk could have several functions connected with sensing, social behavior, feeding, and reproduction.
One major clue is that the tusk is found mainly in males. That difference between the sexes suggests that reproduction plays an important role. NOAA describes the tusks primarily as a secondary sex characteristic. Its size may allow males to assess one another’s status without needing a violent fight. A large tusk may also provide information that matters when females choose mates.
Narwhals are built for life under Arctic ice
The tusk may get most of the attention, but the rest of the narwhal is also well-suited to an extreme environment. These whales can make deep dives while searching for food. NOAA reports that narwhals can descend to about 3,937 feet and remain underwater for as long as 25 minutes.
They feed at or near the ocean floor in deep water. Their known diet includes Arctic cod, polar cod, turbot, squid, and shrimp. Instead of using large visible teeth to grab and chew prey, narwhals can create suction with their mouths to pull food inside.
Much about the narwhal remains a mystery
Scientists now know far more about narwhals than people did in the past. They know that the tusk is a tooth. They have found strong evidence that it has sensory abilities. Researchers understand much about where narwhals migrate, what they eat, how deeply they dive, and how their groups change between seasons.
Yet major questions remain. Even the full purpose of the tusk is still being studied. Its sensory abilities are real, but reproduction also appears to be important. Social behavior and feeding may provide additional explanations. Instead of revealing one clear purpose, research has shown that the strange tooth may perform several roles.
Featured Image: Photo by Nomad Sabor on Unsplash
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