This Eel Fires Extra Alien Jaws Out of Its Throat

That white bit you see emerge from the moray eel’s throat is a second set of jaws that grab the prey and transport it into the bowels of everlasting hell its gullet.

In Alien, which I saw when I was a kid but was too scared to keep my eyes open enough to really watch, people are on a spaceship, then there’s a guy who has, like, tummy problems or something, and finally the big alien enjoys a nice spacewalk. Also, I remember that the alien had a mouth that came out of its regular mouth, and whenever I saw it I had a panic attack.

But I’m older and more sensible now and happy to report that I’m over my fear of jaws that come out of jaws. I know because I can watch the incredible GIF above without suffering a conniption fit. That’s a moray eel, and that white bit you see emerging from its throat? It’s a second set of jaws that fire forward and pull prey down its gullet, just like in Alien … or so people who have seen the whole movie tell me.

This is an apex predator that strikes and grasps unfortunate critters in its regular chompers, then hands the prey off to the nasty hooked teeth of the so-called pharyngeal jaws, which send it down the throat whole. As far as we know, it’s the only fish capable of this remarkable feeding behavior.

Oddly, these jaws are present in all bony fishes, said Rita Mehta, a biologist at the University of California, Santa Cruz. “The vast majority of fishes out there,” she said, “they’re not chewing their food with their oral jaws, and so the evolution of the pharyngeal jaws actually enables them to masticate their food.”

These are the jaws that come out of the moray eel’s throat. The yellowish bits you see are plaque buildups, the result of not enough flossing and waaay too much biting off of dentists’ fingers.

But their jaws have nowhere near the dexterity of those in the 200-odd species of moray eel. (The man who created the Alien queen, by the way, was unfamiliar with the moray. He just set out to create something sufficiently “frightening and horrible,” to which the eels reply, “Uh, rude.”) So why have the morays evolved such an extreme set of chompers?

Most fishes feed using suction, rapidly gaping their maws to create a vacuum that sucks in prey (some frogs and salamanders do this too, including the Surinam toad–whose babies emerge from under its skin–and the 6-foot giant salamanders of Asia). The bigger the head, the bigger the suction.

Moray eels, though, are conspicuously thin, an adaptation to a life spent hiding in crevices waiting for prey, and are therefore unable to generate this vacuum. In addition, they hunt large prey–some morays can reach 10 feet–and swallow them whole. For this, though, suction feeding is inadequate, like a Roomba trying to suck up a tennis shoe.

“Because eating large prey whole means that you need to have a large gape, and gape size is indirectly related to fluid speed, the larger your gape the slower the fluid speed that you’re capable of generating,” said Mehta. “So if you’re going to eat really big, suction is not the way to do it.”

The moray eel with its mortal enemy, the centimeter.

By adapting its pharyngeal jaws into mobilized graspers, the moray doesn’t need a vacuum to get prey to the back of its throat. Instead, it eats like a snake, except without the venom and self-satisfied little tongue flicks. Snakes move their heads over their prey by “ratcheting” the left and right sides of their upper jaws, constantly maintaining a toothy grip. A moray transferring its prey from its regular teeth to the pharyngeal jaws is functionally quite similar. It’s an innovation, according to Mehta, that may have helped morays ascend the throne of the coral reef food chain.

Every ruler has subjects, and the moray is no exception. In 2006, scientists first described a remarkable alliance between morays and groupers, who with a shake of their heads signal to eels that they want to team up for a hunt. (This, of course, is ridiculous. Nodding means “yes” and shaking means “no.” Though it could be that every day is opposite day under the sea.) If the moray accepts, the two stalk side by side in an incredible feat of interspecies cooperation, shown below.

“Essentially, morays or other eels, like snake eels, can go into tight holes in the reefs and capture fish,” said Mehta. “Those fish that get ‘flushed out’ can then be consumed by the predator hunting with the moray, often a grouper. This is an example of how other fishes can ‘exploit’ the elongate body plan of the eel.”



If the grouper catches sight of prey hiding in coral, it will actually signal to the moray with another head shake–the fish equivalent of the pointed finger. And sure enough, the eel investigates, slipping its highly mucoused body into the tightest of crevices in pursuit of its targets while the grouper blocks off escape routes.

The moray will obviously hang on to whatever prey it can get to first, but this cooperative hunting strategy is exceedingly rare in the animal kingdom. Elsewhere, we see dolphins assisting fishermen in Brazil without a speck of training, or honeyguide birds leading us to beehives, then picking up the scraps once we’ve had our fill.

“Oh my God did I leave the oven on?”

But birds and dolphins have long proven their intelligence to humans. Fish, well, we’ve never accused them of being brainy. Except for my pet goldfish Fins, who sometime in the early ‘90s committed suicide by leaping from his tank in what I’m convinced was an act of full-blown civil disobedience. But the moray-grouper alliance suggests intelligence that goes far beyond ritualistic suicide.

There is still much to be learned about the moray, with this behavior and otherwise. Its mating habits and life cycle are particularly mysterious.

“They have this larval stage that’s really peculiar, it’s known as leptocephalus larval stage,” said Mehta. “And in this larval stage, the babies look nothing like a juvenile eel or an adult eel, and essentially they float around in the ocean for about three months.”

Read more at Wired Science