UW News

Karly Cohen

September 4, 2025

This common fish has an uncommon feature: Forehead teeth, used for mating

An illustration of a fish with teeth in its mouth and teeth on the tip of a trunk-like structure protruding from its forehead.

New findings call into question one of the core assumptions about teeth. Adult male spotted ratfish, a shark-like species native to the eastern Pacific Ocean, have rows of teeth on top of their heads, lining a cartilaginous appendage called the tenaculum, in addition to those in their jaws. They used their tenaculum teeth to grip females while mating in water.