Not much is known about the unicorns of the sea, otherwise known as narwhals.
It’s probably down to the fact that can only be found in arctic coastal waters, which means researchers don’t often get to see their behavior up close.
The narwhal’s defining feature is its long tusk. This tusk is, in fact, a tooth, which grows to more than a metre long.
Marine biologists have long wondered why narwhals have a tusk, but one of the greatest sea-based mysteries has been solved by a documentary filmmaker called Adam Ravetch.
It seems narwhals use their tusks as a sort of weapon. They use it to lash out at arctic cods, which leaves them stunned and immobile for a few split seconds, making them easier to catch.
Watch the narwhal use its tusk to great effect in the video below.