(Press-News.org) PROVIDENCE, R.I. [Brown University] -- Fish are power eaters. In many species, large muscles running along their backs and bellies provide bursts of speed for chasing down prey. Then, at the very instant they close in, they vacuum victims into their suddenly gaping mouths with overwhelming suction. It turns out that these power surges are no anatomical coincidence. A new study shows that largemouth bass get their slurping power from the very same muscles that provide their swimming power.
In the Proceedings of the National Academy of Sciences, Brown University researchers show that the muscles in a bass's head contribute virtually none of the power needed (at its peak it's 15 watts) for the doubling of mouth volume that produces the overwhelming vacuum. Instead, the fish's elaborate arrangement of mouth bones acts more like the passive spokes of an umbrella, driven by the pull of the body's swimming muscles. An evolved linkage between the body and the head transfers the same brawn available for propulsion to the mouth for capturing prey.
In the 1950s, researchers first posited that the body might contribute to suction feeding, but that idea had never been tested and measured in fish as they feed.
"People have been tossing this around for as long as they've been playing with fish heads, which is a surprisingly long time," said study lead author Ariel Camp, who earned her Brown Ph.D. this spring based on the research.
Moreover, in the debate about how fish generate their suction, few if any scientists have given the swimming muscles this much of a role.
"I think everyone would be surprised by the extent to which the swimming muscles are really the source of power," said co-author Elizabeth Brainerd, professor of ecology and evolutionary biology.
The researchers suspect that the same thing is going on in many of the more than 30,000 species of ray-finned fishes.
Voracious vacuum's volume
Camp, Brainerd, and co-author Thomas Roberts, professor of ecology and evolutionary biology, were able to make their findings by recording highly precise 3-D X-ray videos of three bass as they gulped down goldfish in the X-ray Reconstruction of Moving Morphology lab at Brown.
The instrument allowed the researchers to track and visualize how all the bones in each fish's head were moving around. That gave them the means to calculate the change in volume of the mouth many times a second as a fish captured its prey. Those measurements, combined with more conventional data on the water pressure in the mouth, allowed them to calculate the power involved over the course of feeding.
Then the researchers calculated the power produced by each of the muscles in the mouth, as well as the swimming muscles in the body, during the suction action. Their analysis showed that up to 95 percent of the power required for the suction came from the swimming muscles, rather than the mouth. The mouth muscles were simply too weak to produce anything but small amounts of suction.
Evolutionary implications
The findings have intriguing implications for fish evolution and neurobiology and illustrate the limits of muscle in many species.
For example, the results may explain why these fish have evolved the rather complex arrangement of bones in their mouths the way they have. The array apparently works quite well for rapidly opening when yanked upon by those big body muscles via the linkage.
"Our paper is the starting point for answering that question: With the fundamental design of the fish head, should it really be primarily explained on the basis of transmitting this power from the swimming muscles to the head?" Brainerd said.
Meanwhile in the paper, the researchers marvel at the feat of the neuromuscular control that the fish must achieve to be able to abruptly switch from swimming in pursuit of prey to using the very same muscles for producing suction. The muscles must execute very different movements for each activity.
"It's like they are doing a stomach crunch to open their mouth," Roberts said.
In broader considerations of anatomy, the study highlights a point made not only by bass, but by baseball. Smaller muscles can only do so much on their own, Roberts said. Just as bass apparently evolved to draw upon their body's swimming muscles to produce suction, so, too, do pitchers and hitters learn how to move much more than just their arms to throw and hit as powerfully as possible.
"There's only so much power you can get out of muscle," Roberts said. "If you need a really powerful activity, as these fish do, you need a really elaborate pattern of evolution that allows you to recruit more muscles from outside of the head."
Apparently eating, for bass, is a whole body sport.
INFORMATION:
The National Science Foundation funded the study (grants: 0642428, 0840950, 1262156).
Chemists and biologists at UC San Diego have succeeded in designing and synthesizing an artificial cell membrane capable of sustaining continual growth, just like a living cell.
Their achievement, detailed in a paper published in this week's issue of the Proceedings of the National Academy of Sciences, will allow scientists to more accurately replicate the behavior of living cell membranes, which until now have been modeled only by synthetic cell membranes without the ability to add new phospholipids.
'The membranes we created, though completely synthetic, mimic several ...
WASHINGTON (June 18, 2015) -- Research published in the Proceedings of the National Academy of Sciences found that some individuals exposed to HIV-1, but who remain uninfected, have a certain pattern of virus-specific immune responses that differentiated them from individuals who became infected. The findings build upon prior research by studying these responses in the context of a controlled clinical trial, examining a large number of subjects, and by having access to specimens saved before anyone was infected. In the future, this information could be used to assess HIV-1 ...
CHAPEL HILL, NC - Painful insulin injections could become a thing of the past for the millions of Americans who suffer from diabetes, thanks to a new invention from researchers at the University of North Carolina and NC State, who have created the first "smart insulin patch" that can detect increases in blood sugar levels and secrete doses of insulin into the bloodstream whenever needed.
The patch - a thin square no bigger than a penny - is covered with more than one hundred tiny needles, each about the size of an eyelash. These "microneedles" are packed with microscopic ...
New Vanderbilt-led research shows hospitals are doing a better job of using antibiotics less commonly associated with antibiotic resistance to treat children hospitalized with community-acquired pneumonia (CAP).
The report, 'Antibiotic choice for children hospitalized with pneumonia and adherence to national guidelines,' was released today in the journal Pediatrics.
This study was nested within a larger study, the Centers for Disease Control and Prevention (CDC) Etiology of Pneumonia in the Community (EPIC). The multi-center EPIC study was a prospective, population-based ...
DURHAM, N.C. -- Time management isn't just important for busy people -- it's critical for plants, too. A Duke University study shows how two biological clocks work together to help plants deal with intermittent demands such as fungal infections, while maintaining an already-packed daily schedule of activities like growth.
The researchers also identified a gene that senses disturbances in the 'tick-tock' of one clock, and causes the other clock to tighten its timetable. Their work appears in the June 22 issue of the journal Nature.
From daily sleep/wake cycles and fluctuations ...
For diabetics, a quick prick of the finger can give information about their blood glucose levels, guiding them in whether to have a snack or inject a dose of insulin. Point-of-care glucose meters, or glucometers, are also used in the veterinary world to monitor cats and dogs with diabetes or pets hospitalized for other reasons. In both cases, the device's readout can literally be a matter of life and death.
While glucometers have the advantage of being fast and requiring only a small drop of blood, they are not as accurate as some other methods of measuring blood glucose. ...
Mild elevations in blood pressure considered to be in the upper range of normal during young adulthood can lead to subclinical heart damage by middle age -- a condition that sets the stage for full-blown heart failure, according to findings of a federally funded study led by scientists at Johns Hopkins.
A report on the findings of the multicenter study that followed 2,500 men and women over a period of 25 years is published online June 22 in the Journal of the American College of Cardiology.
Persistently elevated blood pressure, or hypertension, is one that tops 140/90, ...
COLUMBUS, Ohio -- A new study shows that captive black rhinos -- but not their wild counterparts -- are at high risk for two common health problems suffered by millions of humans: inflammation and insulin resistance.
The finding suggests captive black rhinos have metabolic problems. In humans, these same conditions can both result from a rich diet and sedentary lifestyle and contribute to obesity and other diseases.
To be clear, this study does not suggest that zoos cause health problems in black rhinos, said Pam Dennis, clinical assistant professor of veterinary preventive ...
WASHINGTON (June 22, 2015) - Young adults who had blood pressure that was elevated but still within normal range for long periods of time were more likely to show signs of cardiac dysfunction in middle age, according to a study published today in the Journal of the American College of Cardiology.
Researchers followed 2,479 men and women for 25 years, conducting health assessments -- including blood pressure readings -- seven times during the study period beginning as part of the Coronary Artery Risk Development in Young Adults, or CARDIA study. Participants ranged in ...
The impact of cancer treatments on cardiovascular health is an important consideration when treating cancer patients, but many hospital training programs have no formal training or services in cardio-oncology and a lack of national guidelines and funding are frequent barriers to establishing such programs, according to a nationwide survey published today in the Journal of the American College of Cardiology. The ACC conducted the survey to determine the existing practices and current needs in this area and plan for a cardio-oncology section that would fill gaps in resources ...
