Ever heard of a fish with a mouthful of teeth on its forehead? That’s not science fiction—it’s the wild reality of the ghost shark, and scientists are only just now uncovering the jaw-dropping truth behind this deep-sea oddity.

Deep beneath the ocean’s surface lurks the ghost shark, a mysterious creature related to sharks and rays, but with a secret weapon that’s sending shockwaves through the scientific community. Male ghost sharks, formally known as chimaeras, sport a bizarre rod jutting from their foreheads, covered in rows of sharp, retractable teeth. And these aren’t just intimidating accessories—brand new research reveals these are real teeth growing outside the mouth, used in one of nature’s strangest mating rituals.

This forehead rod, called a tenaculum, is exclusive to males and acts almost like a Swiss Army knife during reproduction. Instead of relying solely on their mouths, male ghost sharks use this toothy appendage to latch onto females, similar to the way sharks use their jaws during mating. It’s a twist on evolution that’s got scientists seriously rethinking what they know about how—and where—teeth can actually grow!

Gareth Fraser, Ph.D., a leading biologist from the University of Florida, helped spearhead the study, collaborating with experts from the University of Washington and the University of Chicago. By examining both 315-million-year-old fossils and living ghost shark specimens from Puget Sound, the team connected ancient and modern dots. They used high-tech CT scans and genetic tests, revealing that these forehead teeth aren’t just cosmetic—they express the exact same genes as true oral teeth, never found in shark skin denticles. Basically, these aren’t wannabe teeth—they’re the real deal, just in a wild new location.

But why the forehead? Turns out, evolution doesn’t follow a rule book. The tenaculum is a relic that evolution repurposed, shortening over time while still maintaining its jaw-teeth-making superpower. As Michael Coates from the University of Chicago put it, it’s a prime example of nature’s “evolutionary tinkering”—using old genetic blueprints to build something entirely new and crucial for survival.

Karly Cohen, a postdoc at the University of Washington, was floored by the discovery, noting that this is the first documented case of real teeth forming outside the jaw in vertebrates. The research, just published in the Proceedings of the National Academy of Sciences, suggests the ocean is still full of surprises, with creatures like the ghost shark showing us just how endlessly creative evolution can be.

This AI generated newscast about ghost sharks’ forehead teeth proves that the mysteries of the deep sea are far from solved. Next time someone says they’ve got a big head, just remember: at least it’s not covered in teeth!