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Study: Fish Use Whole Bodies When They Eat

  • Rosanne Skirble

Fish exercise their entire body to eat.

New research published in the Proceedings of the National Academy of Sciences finds that both head and body muscles help them gulp down prey in one explosive action.

About half of all vertebrates — animals with backbones — are fish with bony fins or spines. These 30,000 ray-finned fish species have evolved this similar feeding motion. Scientists have long hypothesized about the mechanics of the process, but now researchers at Brown University have X-ray video proof of how it works.

The researchers set up a tank in the X-ray Reconstruction of Moving Morphology lab at Brown to watch a largemouth bass as it swallowed a goldfish.

“Those tools were a combination of high-speed X-ray videos combined with CT measurements of bones of the skull in the bass and pressure probe measurements of the pressure in the water during suction feeding,” said Brown biology professor Thomas Roberts, co-author of the study.

But muscles in the head aren’t powerful enough alone to create that suction.

Roberts said what they observed were “incredible linkages of skull bones to pull power from the body muscles to generate the really rapid motion in the head and generate suction to pull in prey.”

The analysis showed that up to 95 percent of the power required for suction came from the swimming muscles.

Roberts said the finding was important to understand how not only bass but also thousands of other species of marine vertebrates have evolved.

“This tells us that this clever co-opting of swimming muscles to produce a feeding motion maybe was really important for the evolutionary success of bony fishes,” he said.

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