Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

How Fish Swim: McCormick Researchers Examine Mechanical Bases for the Emergence of Undulatory Swimmers

25.06.2013
Findings could provide insights in evolutionary biology, neural control of movement, bio-inspired devices
How do fish swim? It is a simple question, but there is no simple answer.

Researchers at Northwestern University have revealed some of the mechanical properties that allow fish to perform their complex movements. Their findings, published on June 13 in the journal PLOS Computational Biology, could provide insights in evolutionary biology and lead to an understanding of the neural control of movement and development of bio-inspired underwater vehicles.

“If we could play God and create an undulatory swimmer, how stiff should its body be? At what wave frequency should its body undulate so it moves at its top speed? How does its brain control those movements?” said Neelesh Patankar, professor of mechanical engineering at Northwestern’s McCormick School of Engineering and Applied Science. “Millennia ago, undulatory swimmers like eels that had the right mechanical properties are the ones that would have survived.”

The researchers used computational methods to test assumptions about the preferred evolutionary characteristics. For example, species with low muscle activation frequency and high body stiffness are the most successful; the researchers found the optimal values for each property.

“The stiffness that we predict for good swimming characteristics is, in fact, the same as the experimentally determined stiffness of undulatory swimmers with a backbone,” said Amneet Bhalla, graduate student in mechanical engineering at McCormick and one of the paper’s authors.

“Thus, our results suggest that precursors of a backbone would have given rise to animals with the appropriate body stiffness,” added Patankar. “We hypothesize that this would have been mechanically beneficial to the evolutionary emergence of swimming vertebrates.”

In addition, species must be resilient to small changes in physical characteristics from one generation to the next. The researchers confirmed that the ability to swim, while dependent upon mechanical parameters, is not sensitive to minor generational changes; as long as the body stiffness is above a certain value, the ability to swim quickly is insensitive to the value of the stiffness, the researchers found.

Finally, making a connection to the neural control of movement, the researchers analyzed the curvature of its undulations to determine if it was the result of a single bending torque, or if precise bending torques were necessary at every point along its body. They learned that a simple movement pattern gives rise to the complicated-looking deformation.

“This suggests that the animal does not need precise control of its movements,” Patankar said.

To make these determinations, the researchers applied a common physics concept known as “spring mass damper” — a model, applied to everything from car suspension to Slinkies, that determines movement in systems that are losing energy — to the body of the fish.

This novel approach for the first time unified the concepts of active and passive swimming — swimming in which forcing comes from within the fish (active) or from the surrounding water (passive) — by calculating the conditions necessary for the fish to swim both actively and passively.

The paper, “A Forced Damped Oscillation Framework for Undulatory Swimming Provides New Insights into How Propulsion Arises in Active and Passive Swimming,” was authored by Patankar, Bhalla, and Boyce E. Griffith, assistant professor of medicine and mathematics at New York University.

The work was supported by the National Science Foundation (NSF).

Megan Fellman | EurekAlert!
Further information:
http://www.northwestern.edu

More articles from Life Sciences:

nachricht New risk factors for anxiety disorders
24.02.2017 | Julius-Maximilians-Universität Würzburg

nachricht Stingless bees have their nests protected by soldiers
24.02.2017 | Johannes Gutenberg-Universität Mainz

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Stingless bees have their nests protected by soldiers

24.02.2017 | Life Sciences

New risk factors for anxiety disorders

24.02.2017 | Life Sciences

MWC 2017: 5G Capital Berlin

24.02.2017 | Trade Fair News

VideoLinks
B2B-VideoLinks
More VideoLinks >>>