They are distinctive for the long tusk that protrudes from their head but until now nobody had a clue why the Narwhal evolved like it did.
Thanks to a scientific break though, biologists now believe that the horn of the male of the species is in fact a sensory organ.
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Commonly referred to as the unicorn of the sea – but perhaps lacking the majesty of their mythical counterparts – it was previously thought that the unusual feature could be used for contests between males or as an ice pick.
The tusk is actually the left canine of the toothed whale which breaks through its upper lip.
But unlike a normal tooth it has no enamel, making it porous and meaning sea water can travel through the tusk connecting with nerve endings and then, most importantly, sending signals to the brain.
This gives the horn a sensitivity to different chemical in the water, writes Tech Times.
Researchers believe it could be used to find females and food.
‘The combined evidence suggests multiple tusk functions may have driven the tooth organ system’s evolutionary development and persistence,’ they wrote in the study.
The Narwhal lives year round in Arctic waters near Greenland, Canada and Russia.
It can grow up to 18 feet in length, excluding the tusk which can grow for another eight feet.
The whale can live up to 50 years old with its diet consisting mainly of Arctic cod.