Moray eels have a problem. Like other eels, they are the descendants of fish that use a method called gape suction feeding in order to gather food. Essentially, this requires a mouth that can expand very rapidly, creating a huge rush of water into the fish’s mouth, and dragging along any prey item caught in the wake. Eels, though, because of their slender bodies and specialized skull, don’t have the gape to create the suction needed to eat this way. So, in order to pull food into their mouths and down into their throats, moray eels have evolved a second set of jaws.
Derived from gill arches, these jaws sit in the back of the moray’s throat. When an eel bites down on a prey item, these jaws swing forward, grasp the prey, and then move backwards in order to pull the food down into the eel’s throat.