Moray eels have a unique way of feeding reminiscent of a science fiction thriller, researchers at UC Davis have discovered. After seizing prey in its jaws, a second set of jaws located in the moray's throat reaches forward into the mouth, grabs the food and carries it back to the esophagus for swallowing.

"This is really an amazing innovation for feeding behavior for fishes in general," said Rita Mehta, a postdoctoral researcher in the Section of Evolution and Ecology at UC Davis.

The research shows the amazing diversity possible among living things, even in something as fundamental as feeding, Mehta said.

The research, documented in a paper, was the subject of an article in the Sept. 6 issue of the journal Nature.

Mehta worked in the laboratory with a high-speed digital camera to document eels feeding -- and captured the rapid movement of these secondary pharyngeal jaws. She used X-ray and other imaging equipment at the UC Davis School of Veterinary Medicine to work out how the jaws could move.

More than 200 species of moray eels are found in tropical waters worldwide, often living in holes in rocks and coral reefs. In the wild, they can reach 10 feet in length.

Most fish feed by suction. When a fish comes upon food or prey, the fish rapidly expands its mouth cavity, sucking in water and the food with it. Some fish feed by overtaking prey with their mouth open or grabbing the prey in their jaws, but most of those fish then use suction to move the food from the mouth to the esophagus.

But moray eels have little ability to generate suction through their mouths, Mehta found. Instead, they first grasp food with their powerful, toothsome outer jaws. Then the pharyngeal jaws, armed with large, curved teeth, reach forward and seize it. At the same time, the outer jaws release the prey and the pharyngeal jaws bring it back for swallowing. The whole process takes just fractions of a second.

Other fish are known to have pharyngeal jaws that can grind or crush food, but "nothing this spectacular," said Peter Wainwright, professor of evolution and ecology at UC Davis and co-author with Mehta on the paper. Only the moray eel seems to have a second, mobile set of jaws that can reach forward and grab prey.

Mehta compared the eels to snakes, which also must fit large food items through relatively narrow mouths into long, thin bodies. Snakes solve the problem by "ratcheting": They can separate the left and right sides of the jaw, holding onto the food with one side while working the other side around the food.

Mehta and Wainwright are now investigating how the morays' extraordinary jaws evolved. Other species of eel, such as the American eel Anguilla, feed by suction. Moray eels may have evolved other methods as a result of hunting in confined spaces, where the animals could not rapidly expand their heads to create suction.

"Eels are an amazingly diverse and bizarre group of fishes, and not very well known," Wainwright said.

Grants from the American Association of University Women and the National Science Foundation supported the initial research.

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The National Science Foundation’s Web site features a graphic, photos and a video: www.nsf.gov (search for Press Release 07-113).