After stalking an unsuspecting cuttlefish across the seafloor, this moray eel is finally ready to pounce.
As the eel snags the mollusk in its long teeth, its prey struggles to escape.
But before it can wriggle away, a second set of teeth lunge from the eel's throat, making short work of the captive cuttlefish.
This adaptation is called a pharyngeal jaw.
And while it might seem more fitting for an alien parasite than a fish, it's actually one of the most common adaptations under the sea.
At some point millions of years ago, early fish evolved a jointed oral jaw from one of the bony arches that supported their frontal gills.
This exterior, oral jaw was perfect for capturing or chewing prey, but these early fish had a problem.
They had no limbs to manipulate food while eating, making it easy for their mobile prey to escape before they took the first bite.
Essentially, it was impossible for fish to capture and chew their prey at the same time with just one set of jaws.
So to hold their food and eat it too, an even deeper gill arch evolved into a secondary set of jaws.
