Narwhals are the Unicorns of the sea - and now, researchers know why the whales sport that distinctive horn....

Although biologists knew this much about the horn of narwhals, theories of how the animals used the body part differed greatly. Some biologists believed the horns are used for ice picks, while others said the horns picked up noises deep under water. Researchers discovered the horn is, in fact, used as a sensory organ.

Unlike most mammal teeth, the horn of a narwhal is not protected by enamel. Sea water enters the horn through cementum channels, which are also present in human teeth. The liquid then travels through a network of tubules to the center of the tooth, heading base of the tusk. There, the water excites nerve endings in the pulp of the tooth, sending signals to the brain of the animal.

This makes the horn sensitive to temperatures and the animal can "taste" the concentrations of different chemicals in the water. Biologists believe the males may use the horn to find food, as well as females who may be ready to mate.