52: Narwhals

Time for another animal spotlight, and this week it’s the majestic narwhal! For a long time this animal was believed to be magical, then imaginary. We still know very little about it, but the more we are learning the more amazing it seems to be! This week we will explore where it lives, what that giant tusk does, and how they have some pretty sophisticated social behaviour. Oh, and we’ll also be exploring what a narluga is. Enjoy!

A narwhal is a toothed whale, known to be small. Though small compared to many other whales, they are still relatively large animals, growing up to 5.5 meters in length with a 3meter long tus (Picture: Encyclopaedia Britannica).

Lifestyle

Narwhals are what are considered small whales (though they’re really not that small…) which are found in Arctic rivers and seas in Eastern Canada, around Greenland, and in high Arctic waters above Scandinavia and western Russia. They fall into the toothed whale group, along with orcas, dolphins and porpoises because, well, they have teeth. The other whale group is the baleen whales, who have baleen plates that look almost like hairs, and which they use to filter food out of water. Baleen whales tend to be bigger in size, including species like the Blue Whale.

Though considered small, narwhals can be anything between 4-5.5 m in length and weigh 800-1,600 kg. They tend to travel in groups of around 15-20, though in some cases thousands have been seen swimming together. Narwhals feed off fish, shrimp and squids and are hunted by orcas and occasionally polar bears, walrus’ and humans.

The number of narwhals is sort of unknown, but thought to be around 123,000 individuals. Whether their population is going up or down is also unknown. They are quite elusive animals and they tend to live in very hard to reach areas so are not the easiest to study. There is a decrease in the quality of their habitat happening though, and concerns about the effects of climate change on them especially decreases in sea ice. However, their numbers appear to be reasonably stable and aside from temporary bans on the trade of their tusks from the EU, Greenland and Canada over the years, they are allowed to be hunted and their tusks sold according to set quotas.

Narwhals are sociable animals, normally travelling in groups of 15-20, though they have been seen in groups of thousands. (Picture: Marinebio.org)

Tusk

Of course, the most noticeable thing about a narwhal is its long tusk, which can grow to over 3 m in length. This tusk is actually a tooth, one of two teeth that these whales have at the front of their mouths. In males, the left tooth grows into a huge tusk, whilst the right one usually stays within the skull, whilst in females both usually stay within the skull. There are some rare cases where a narwhal develops both teeth into tusks.

There are many theories on what this tusk does. It is known to have millions of nerve endings within it which may be used to detect the levels of salt in the water, and though previously thought to be a sign of aggression, males rubbing their tusks against one another is now thought to be some kind of communication, perhaps sharing information on the conditions of waters they have travelled through recently. A video recorded in 2017 showed another potential use- for hunting. The recording showed narwhals using their tusk bop cod on the head, making them easier to catch and eat. Despite all these theories, the tusk is not thought to be essential for their survival as females manage without them, and so it is also believed part of their role is in sexual selection i.e. lady narwhals like a guy with a nice tusk, kind of like how lady peacocks like a man with a fabulous tail. We all have our preferences!

On the left a male and female narwhal skull showing the growth and dormancy of the two prominent front teeth in their skull. On the right the skull of a narwhal with the unusual mutation of having grown out both teeth, creating two tusks.

Hybrids and menopause

Narwhals are a surprisingly long-lived animal, surviving an average of around 50 years but with some of the oldest being between 105-125 years old. Not only this but the females go through menopause which is highly unusual in the animal kingdom. In fact, other than humans only five other species are known to go through the menopause and they are all toothed whales. Normally it would be biologically beneficial to have as many offspring as possible for as long as possible. However, studies on orcas, who also go through menopause, suggest that because these whales stay with their families for life, if a female keeps on producing, her children will be directly competing with her grandchildren and great grandchildren for food. Instead, by going through the menopause a female can allow her children to continue producing descendants, whilst she saves her energy and provides a more guiding role to the group, using her knowledge and experience to e.g. help them find food. It is thought the reason for menopause in narwhals might be the same.

Baby narwhals, called calves, are born in what are known as nurseries. These are usually inlets where mothers go to give birth and start raising their young before taking them out into the big wide ocean. Females only have one calf at a time. Interestingly, narwhals have been seen to interbreed in a few rare cases with a close relative of theirs, the beluga whale. This information came from a Greenlandic hunter who had caught the hybrid calf and noticed it was unusual. The skull was later examined by scientists who could see that it was the offspring of a female narwhal and male beluga. Even more interestingly it seems that this hybrid grazed on fish on the sea bed, a behaviour seen in neither of its parents. However, as there are only three cases of this hybridisation and all the data scientists have collected on them have been based on their bones and the stories of hunters, little is known about them. Some call this hybrid a beluwhal, though personally I prefer narluga. If you’re wanting more info on animal hybrids, I recommend plog 14: Species, pizzlies and mules.

Though less showy without the tusk, older female narwhals are thought to play an important role in guiding their group to find food. (Picture: Getty Images)

Myth and Legend

Of course, you can’t have something like a 3 m long tusk without creating some myth and legend around it. In medieval times in Europe the narwhal tusk was believed to be a unicorn horn, and as such had special magical powers, allowing them to neutralise poison and cure ‘melancholy’. The enterprising Vikings were able to sell them far and wide on this premise for a high price.

In some Inuit cultures the tusk was said to be created when a woman struck a narwhal with a harpoon which she had tied around her waist, but was pulled into the sea after it. She them became a narwhal, her hair creating the spiral pattern on the narwhal tusk.

Even as far back as the times of the ancient Greeks, physicians like Ctesias believe unicorn horns could remove poison from food. On the left is shown an experiment conducted using a unicorn horn to see how effective its properties were. In reality a narwhal tusk was used but, you know, close enough. Rhino horns and walrus teeth were also sometimes used. On the right a pharmacy sign making use of a narwhal tusk (Pictures: Images/CC)

Elusive and somewhat inconclusive, we still have a lot to learn about narwhals. They are a visually striking creature thanks to their tusks, but they also seem to have complex social behaviours with wise old females guiding families with their knowledge and experience, and sociable males sharing with one another news of the waters they have recently been through. Whether they can cure melancholy is a bit tenuous, but looking at this buck toothed beauty can certainly bring a smile!

For more info:

A video of narwhals using their tusks to stun cod:

The scientific paper discussing the finding of the hybrid beluwhal/narluga:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6586676/

Music: kongano.com

Cover picture: University of Washington Magazine

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