The Narwhal's Unique Sensory Organ

By Cécile Dumas, Le Nouvel Observateur

Translated from French using Google Translate

After fueling one of the most famous myths—that of the unicorn—the narwhal's rostrum continues to amaze scientists. What is the purpose of the marine mammal's long spiral tooth? Without providing a definitive answer, Martin Nweeia and his colleagues shed new light on this appendage: contrary to appearances, it is very sensitive. The researchers discovered that the narwhal's tooth was very richly innervated.

Researchers observed that millions of nerve connections go from the heart of the tooth to the outside. Even more curious: the small canals connected to the nerves and the pulp are open on the surface of the tooth. The rostrum is therefore like a membrane with a very sensitive surface. There is no tooth in nature comparable in size and function, believes Martin Nweeia, a specialist in dentition and biomaterials at Harvard Medical School. He is surprised that an animal living in an icy environment has developed such a sensitive tooth.

It remains to be explored the functions of this tooth, which measures up to 3 meters long and is almost exclusively the preserve of males. Until now, it was thought that the rostrum could be used to search for food, court females, establish a dominant status, break the ice, etc. Some of these explanations fall flat, others remain valid.

Knowing the sensitivity of the rostrum, some behaviors of narwhals can be interpreted differently. It often happens that two narwhals rub their rostrum against each other. Is this a way of measuring each other between males or, more prosaically, a way of ridding the tooth of limestone or shells that are encrusted? The narwhal is ultimately a more mysterious animal than the unicorn.