Navigation Links
A fish that pushes in the wrong direction solves a mystery of animal locomotion

For nearly 20 years, Professor Eric Fortune has studied glass knifefish, a species of three-inch long electric fish that lives in the Amazon Basin. In his laboratory he tries to understand how their tiny brains control complex electrical behaviors. But he could not help but be intrigued by the special "ribbon fin" that knifefish use to swim back and forth. The fin oscillates at both ends, allowing the fish to move forward or backward. Biologists have long wondered why an animal would produce seemingly wasteful forces that directly oppose each other while not aiding its movement.

But in the Nov. 4-8 online edition of Proceedings of the National Academy of Sciences (PNAS), Fortune and a multi-disciplinary team of researchers report that these opposing forces are anything but wasteful. Rather, they allow animals to increase both stability and maneuverability, a feat that is often described as impossible in engineering textbooks.

"I read a Navy flight training manual that had a full page dedicated to the inherent tradeoff between stability and maneuverability, says Fortune, an associate professor of biology at NJIT. "Apparently the knifefish didn't read that manual, since the opposing forces surprisingly make the fish simultaneously more stable and more maneuverable."

When an animal or vehicle is stable, it resists changes in direction. On the other hand, if it is maneuverable, it has the ability to quickly change course. Generally, engineers assume that a system can rely on one property or the otherbut not both. Yet some animals prove an exception to the rule.

"Animals are a lot more clever with their mechanics than we often realize," said Noah Cowan, a professor of mechanical engineering at The Johns Hopkins University and the senior author of the multi-disciplinary research team. "By using just a little extra energy to control the opposing forces, animals seem to increase both stability and maneuverability when they swim, run or fly."

And Fortune suspects that the study will inspire young engineers to approach mechanical design in novel ways. "Despite the fact that the knifefish break a traditional rule of engineering," says Fortune, "they nevertheless achieve better locomotor performance than current robotic systems."

To conduct its study, the team used a combination of careful observations of the fish, mathematical modeling and an analysis of a swimming robot. Working in his NJIT lab with students and in collaboration with his colleagues at Johns Hopkins, Fortune used slow-motion video to film the fish to study its fin movements: What the videos revealed was startlingly counterintuitive.

"It is immediately obvious in the slow-motion videos is that the fish constantly move their fins to produce opposing forces," says Fortune. "One region of their fin pushes water forward, while the other region pushes the water backward. This arrangement is rather counter-intuitive, like two propellers fighting against each other."

A mathematical model designed by Shahin Sefati, a graduate student at Johns Hopkins and a lead author of the research project, showed that this odd arrangement generates stabilizing forces. But the model also suggested that the opposing forces simultaneously improved the ability of the animal to change its velocity, thereby making the animal more maneuverable. The team then tested this model using a robot in the laboratory of Malcolm MacIver at Northwestern University; the robot mimicked the fish's fin movements.

One exciting implication of study is its possible application to robotics systems, including the design of sophisticated robots and aircraft. Designers and engineers might make simple changes to propulsion systems, such as tilting engines or motors so that some of the thrusts oppose each other. Such an arrangement might waste some energy, but this cost may be more than offset by making a robot or aircraft simpler to operate and thus safer.

Fortune joined the NJIT faculty last year as part of a university initiative to increase interdisciplinary research.

"This study is a good example of how engineers can look to nature with the tools of biology to inspire new approaches to solving fundamental design challenges in engineering," says Fortune. "In the other direction, biologists benefit from the application of the analytic tools and quantitative approaches that are routine in engineering. NJIT, with its focus on interdisciplinary research, is just the ecosystem we need to translate these ideas into new technologies."


Contact: Tanya Klein
New Jersey Institute of Technology

Related biology news :

1. Report: Bushmeat pushes Southern African species to the brink
2. Wind pushes plastics deeper into oceans, driving trash estimates up
3. 2 genetic wrongs make a biochemical right
4. Mutation causing wrong-way plumbing explains 1 type of blue-baby syndrome
5. Platinum is wrong stuff for fuel cells
6. How bacteria change movement direction in response to oxygen: Molecular interactions unravelled
7. Researchers call for a new direction in oil spill research
8. Harvard and USC scientists show how DHA resolves inflammation
9. Chemistry resolves toxic concerns about carbon nanotubes
10. Team solves birth and migration mysteries of cortexs powerful inhibitors, chandelier cells
11. After 121 years, identification of grave robber fossil solves a paleontological enigma
Post Your Comments:
(Date:3/27/2017)... , March 27, 2017  Catholic Health ... and Management Systems Society (HIMSS) Analytics for achieving ... Adoption Model sm . In addition, CHS previously ... U.S. hospitals using an electronic medical record (EMR). ... its high level of EMR usage in an ...
(Date:3/24/2017)... Research and Markets has announced the addition of the ... Industry Forecast to 2025" report to their offering. ... The Global Biometric Vehicle Access ... 15.1% over the next decade to reach approximately $1,580 million by ... and forecasts for all the given segments on global as well ...
(Date:3/23/2017)... Research and Markets has announced the addition of the ... Forecast to 2025" report to their offering. ... The Global Vehicle Anti-Theft System ... over the next decade to reach approximately $14.21 billion by 2025. ... forecasts for all the given segments on global as well as ...
Breaking Biology News(10 mins):
(Date:10/10/2017)... SANTA CRUZ, Calif. , Oct. 10, 2017 /PRNewswire/ ... SBIR grant from the NIH to develop RealSeq®-SC (Single ... preparation kit for profiling small RNAs (including microRNAs) from ... Cell Analysis Program highlights the need to accelerate development ... "New techniques for ...
(Date:10/9/2017)... Jupiter, FL (PRWEB) , ... October 09, 2017 , ... ... episode, scheduled to broadcast first quarter 2018. American Farmer airs Tuesdays at 8:30aET on ... Agriculture industry is faced with the challenge of how to continue to feed a ...
(Date:10/7/2017)... ... October 06, 2017 , ... ... and applications consulting for microscopy and surface analysis, Nanoscience Instruments is now ... Analytical offers a broad range of contract analysis services for advanced applications. ...
(Date:10/6/2017)... D.C. (PRWEB) , ... October 06, 2017 , ... ... will host a lunch discussion and webinar on INSIGhT, the first-ever adaptive clinical ... Principal Investigator, Dana-Farber Cancer Institute. The event is free and open to the ...
Breaking Biology Technology: