Scientists uncover hidden opposite spiral inside narwhal's iconic tusk

A paper in Nature Communications reports that the famous narwhal tusk houses a concealed internal spiral that twists opposite to the visible outer helix. The tusk is a left upper-jaw canine tooth that begins to protrude when males are two to three years old and can grow to lengths of 1.5 to 2 meters. Some males develop two tusks or none at all, while females typically have only small, less-spiraled versions, supporting the idea that the structure arose from sexual selection rather than survival necessity.

The study notes that the tusk contains several million nerve endings, hinting at a possible sensory role for temperature or salinity changes. Narwhals have been observed using their tusks to stun Arctic cod, and occasional findings of tusks embedded in other narwhals suggest a combat function, though direct observation is lacking. Inuit folklore links the spiral to a legend of a woman transformed into a narwhal, underscoring the cultural fascination with the organ.