To Capture Prey on Land, This Eel Has an Extendable, Extra Jaw Hidden Inside Its Throat

This second set of teeth allows some moray eels to more effectively feed in the intertidal zone when the tide is low

snowflake moray eel
A snowflake moray eel peers out from its hiding spot. Bernard Spragg via Flickr under CC0 1.0

Researchers studying moray eels have discovered that these serpentine fishes have a freaky second set of razor-toothed jaws that help the eels reel in prey, even on land, according to new study published earlier this month in the Journal of Experimental Biology.

Nearly all fish feed underwater, and most predatory fish take advantage of the properties of their liquid medium by generating intense suction to hoover their favorite prey down their gullet. But this tactic doesn’t work so well on land, and some moray eels are known for wriggling around out of the water during low tides in search of crabs and other intertidal delicacies.

The study is the first to document how the moray’s special extra set of jaws swings forward from the back of the eel’s throat to latch onto food and drag it back towards the stomach without relying on suction like ordinary fish, reports Mindy Weisberger for Live Science.

Study author Rita Mehta, an evolutionary biologist at the University of California Santa Cruz, tells Live Science that based on what she knew about how these eels use these extra jaws to pull in food, “it made sense that if morays were able to capture prey in the intertidal or on land, they could also swallow their prey on the land without relying on water."

To put this idea to the test, Mehta and her colleagues set up an experiment with a team of specially trained snowflake moray eels and tempted them with morsels of squid dangled over dry land, reports Sabrina Imbler for the New York Times. In videos of the experiment, an eel hurls its body up a sandy ramp and grabs the piece of squid with its visible, standard-looking jaws only to suddenly slingshot the squid deeper into its mouth with an unseen flick of its second set of chompers, known as pharyngeal jaws.

Snowflake morays can feed on land, swallow prey without water

“Most fishes really need water to feed,” says Mehta in a statement. “This is the first example of a fish that can feed on land without relying on water.”

Having pharyngeal jaws isn’t so weird, all bony fishes have them, what sets morays apart is how those extra jaws, located just behind the throat or pharynx, can move, according to Live Science.

“They have highly moveable pharyngeal jaws in their throat,” says Mehta in the statement. “Once the moray captures prey in its oral jaws, the pharyngeal jaws grab onto the prey again and move it further back into the esophagus. This mechanical movement does not rely on water.”

Not relying on water means that a moray eel foraging on land can snarf down dinner without needing to call off the hunt by returning to the water.

“Fish are mostly suction feeders and catch prey by sucking water in the mouth,” Peter Wainwright, a fish biomechanics expert at the University of California, Davis, who was not involved with the new research, tells the Times. However, Wainwright adds, “morays have evolved away from suction feeding.”

By doing so, “these particular morays can utilize very different environments for food resources,” says Mehta in the statement.

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