Ghost sharks grow forehead teeth to help them have sex
Male “ghost sharks” — eerie deep-sea fish known as chimaeras that are related to sharks and rays — have a strange rod jutting from their foreheads, studded with sharp, retractable teeth. New research reveals these are not merely lookalikes, but real rows of teeth that grow outside the mouth.
What’s more, the toothy appendage is likely used for mating. Found only in males, the forehead rod — called a tenaculum — is the ghost sharks’ only source of distinct teeth, and it seems to be used to grasp females in much the same way sharks use their toothy mouths in mating.
“If these strange chimaeras are sticking teeth on the front of their head, it makes you think about the dynamism of tooth development more generally,” said Gareth Fraser, Ph.D., a professor of biology at the University of Florida and senior author of the study. “If chimaeras can make a set of teeth outside the mouth, where else might we find teeth?”
