Fish are animals that live in the water. They are alsovertebrates – animals that have a backbone and a spine. They have gills thatpermit them to take oxygen from the water. But have you ever wondered howvertebrates eat food? Now researchers at Brown University have x-ray videothat shows the action in great detail.

Many fish are power eaters. Bass, for example, can eat goldfish in one bigswallow. Thomas Roberts is a biology professor at Brown University. He andhis co-workers used new tools to record the fish’s movements as it ate.

"And those tools were a combination of high speed x-ray videos combinedwith CT measurements of the bones of the skull in the bass and pressureprobe measurements of the pressure in the water during suction feeding."

Thomas Roberts says the muscles in the head are not powerful enough tocreate that suction. He says they must work together with the body musclesused for swimming. Scientists had suspected this cooperation in the past, but, until now, they had no proof.

"Fish actually have to use this incredible linkages of skull bones to pull powerfrom the body muscles to generate the really rapid motion in the head andgenerate suction to pull in prey."

The finding is important to understand how not only bass, but some 30,000species of water vertebrates evolved. Thomas Roberts explains.

"So this tells us that this clever co-opting of swimming muscles to producea feeding motion maybe was really important for the evolutionary success ofbony fishes."

The study was published in the Proceedings of the National Academy ofSciences.

I’m Marsha James.

VOA correspondent Rosanne Skirble reported this story from Washington.Marsha James adapted it for Learning English. Caty Weaver was the editor.

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Words in This Story

swallow– n. taking something into your stomach through your mouth andthroat

suction – n. the act or process of grasping something

incredible– adj. difficult or impossible to believe

generate – v. to produce (something) or cause (something) to be produced

rapid– adj. happening in a short amount of time

prey– n. an animal that is hunted or killed by another animal for food

clever – adj. intelligent and able to learn things quickly

co-opt– v. to cause or force something to work with something

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