Males may use their tusks in fights with other males to establish social hierarchies. Tusks could also be used for breaking through thin layers of ice in their freezed ocean habitate.

 

Researchers from Harvard School of Dental Medicine think the giant tooth might also act as a sensory organ. With the electron microscope, they discoveried that the surfaces of narwhal's tusk is covered with millions of tiny nerventings. These nerves connected to the narwhal's brain through a network of tiny tubes in the tooth.

 

The scientists believed that the narwhals used the sensitive tusks to detect changes in temperature, solt content, and flow patterns in the environment around them. But since only males grow tusks, it's likely that the tusks did not evolve primarily as a sensory organ, more researchers need to really understand why narwhals have tusks, and how they use them.