Bass swimming muscles pull double-duty, study finds

Chuck Bednar for redOrbit.com – @BednarChuck

Bass are well known for their swimming aptitude, but new research published Monday in the journal Proceedings of the National Academy of Sciences reveals that the same muscles that help the fish travel under water also help it capture its prey.

In their new study, lead author Ariel Camp, who earned a Ph.D. at Brown University in Rhode Island this spring, and her colleagues found that the muscles in the head of a bass contribute virtually none of the power needed to double its mouth volume and produce the overwhelming suction force required to ingest their meals.

Instead, they found that the arrangement of bones in the fish’s mouth are actually driven by the pull of the body’s swimming muscles, which run along their backs and bellies and give them the speed required to catch up to their prey. A complex network allows the same muscles responsible for propulsion to transfer power to the head, doubling the mouth volume.

“In fish, the body muscles are generally synonymous with swimming muscles,” Dr. Camp told redOrbit via email. “But our discovery shows that is just half the story. These body muscles are both swimming and feeding muscles. This changes our understanding of how these muscles have evolved, and recasts the role of body muscles in the over 30,000 species of fishes.”

New imaging technology

According to the study authors, the notion that the body muscles might play some role in suction feeding was first discussed by researchers in the 1950s, but no one had ever previously attempted to test the hypothesis by conducting measurements of fish while they were actively feeding.

Furthermore, few if any researchers had ever considered that the swimming muscles played were this involved in providing power to the mouth muscles for the capture and consumption of prey. So what inspired Dr. Camp’s team to investigate this potential link?

“My colleagues and I were really interested in how fish produce the amazingly powerful motions of suction feeding. There was an idea that body muscles might be contributing some power to feeding, but no one had been able to make the measurements to test this,” she told redOrbit.

“With the new imaging technique of X-ray Reconstruction of Moving Morphology (XROMM), we finally had the tools to put this idea to the test,” Dr. Camp continued. “We expected that the body muscles might generate some power for suction feeding, but we certainly weren’t expecting that they would be producing nearly all the power.”

She added that the findings “also provide insights beyond just fish and feeding, into how muscles function across animals. A small muscle can only produce a limited amount of power, so we might expect very powerful motions to require very large muscles. But just as human athletes learn to use muscles from their legs and trunks to throw or hit a ball, fish have evolved a mechanism to apply power from their large body muscles to move their mouths during feeding.”

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