Narwhal tusk: “most extraordinary” tooth in nature

SIKU CIRCUMPOLAR NEWS SERVICE

A new study by an American dental researcher shows that narwhals use their tusks to determine the salinity of water and search for food.

After four trips to the High Arctic to study narwhals, Martin Nweeia of the Harvard School of Dental Medicine discovered the narwhal’s tooth or tusk is like a giant sensor, with 10 million nerve connections from the central nerve of the tusk to its outer surface. These allow the tusk to detect changes in water temperature.

Nweeia says it’s “the most extraordinary tooth in nature.”

The narwhals’ long tooth emerges from the left side of the upper jaw. Its shape and placement are also unique, and the tusk is found on most males and some females.

“Why would a tusk break the rules of normal development by expressing millions of sensory pathways that connect its nervous system to the frigid Arctic environment?” Nweeia said in a statement. “Such a finding is startling and indeed surprised all of us who discovered it.”

The tusk is also sensitive to touch, and narwhals are known for their “tusking” behavior, when males rub tusks with each other.

“Now that we know the sensory capabilities of the tusk, we can design new experiments to describe some of the unique and unexplained behaviors of this elusive and extraordinary whale,” Nweeia said.

The tusks are both strong and flexible and researchers are trying to find out if narwhal tusks can point to ways of making materials for use in dental reconstructive work.