Dubbed the unicorns of the sea, narwhals are mystical creatures with long spiralling tusks that can grow up to 18ft. Their tusks are thought to be used for spearing fish, warding off predators or as ice-anchors (like walruses). But the truth is that we don’t really know what narwhals use their tusks for, beyond making them look cool. But scientists are trying to find out, using a variety of different approaches and techniques.
For example, a team of marine and developmental biologists, comparative zoologists, dentists and orthopedic surgeons have analysed a dead narwhal’s tusk. They found that the tusks are highly vascularised — in other words, they have lots of blood vessels in them. The researchers suggest this makes them a sort of telepathic antenna, used to detect and transmit information in the form of electrical signals.
The tusks are also known to emit pulsing clicks and whistles, which help narwhals communicate with other whales in their pods. Scientists have discovered that these sounds allow narwhals to create an acoustic image of their environment, similar to the way a flashlight flickering on and off can create a light image on a wall. This is called unihemispherism and it helps narwhals keep aware of their surroundings while conserving energy during stretches underwater.
This is especially important as, unlike most other mammals, narwhals do not sleep while they are underwater. When a narwhal dives, its muscular flap closes to seal off its blowhole. The animal slowly depletes oxygen in its lungs and bloodstream before returning to the surface to breathe again. A narwhal may dive for up to 25 minutes before coming up for air.