Overview
- The cranial appendage, called the tenaculum and located between the eyes, bears seven to eight rows of teeth in sexually mature males.
- Laboratory analyses show activation of the same tooth‑forming genes seen in oral dentition and rule out dermal denticles.
- Males use the dented tenaculum to grasp a female’s pectoral fin during mating and as a visual display to deter rivals.
- The peer‑reviewed study, led by Gareth Fraser and released on October 17, 2025, examined specimens from the northeast Pacific using microscopy, gene expression profiling and micro‑CT.
- Researchers and outside commentators say the finding overturns the assumption that vertebrate teeth are strictly oral and prompts searches for similar traits and developmental mechanisms in other species.