Navigation Links
Northwestern researchers examine mechanical bases for the emergence of undulatory swimmers

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.


Contact: Megan Fellman
Northwestern University

Related biology news :

1. Grants add to Northwestern-Qatar partnership
2. UCSB scientists compile first study of potential for tsunamis in northwestern California
3. Northwestern scientists create chemical brain
4. Study by UC Santa Barbara researchers suggests that bacteria communicate by touch
5. UC Santa Barbara researchers discover genetic link between visual pathways of hydras and humans
6. Researchers attempt to solve problems of antibiotic resistance and bee deaths in one
7. UNH researchers find African farmers need better climate change data to improve farming practices
8. Ottawa researchers to lead world-first clinical trial of stem cell therapy for septic shock
9. Researchers uncover molecular pathway through which common yeast becomes fungal pathogen
10. Researchers print live cells with a standard inkjet printer
11. Columbia Engineering and Penn researchers increase speed of single-molecule measurements
Post Your Comments:
(Date:11/10/2015)... 10, 2015 About signature ... helps to identify and verify the identity of ... as the secure and accurate method of authentication ... particular individual because each individual,s signature is highly ... when dynamic signature of an individual is compared ...
(Date:11/9/2015)...  Synaptics Inc. (NASDAQ: SYNA ), the leading ... into the automotive market with a comprehensive and dedicated ... consumer electronics human interface innovation. Synaptics, industry-leading touch controllers, ... automotive industry and will be implemented in numerous locations ... , Japan , and ...
(Date:11/2/2015)...  SRI International has been awarded a contract of ... to the National Cancer Institute (NCI) PREVENT Cancer Program ... modern testing and support facilities, and analytical instrumentation to ... studies to evaluate potential cancer prevention drugs. ... Drug Development Program is an NCI-supported pipeline to bring ...
Breaking Biology News(10 mins):
(Date:11/24/2015)... -- Cepheid (NASDAQ: CPHD ) today announced that ... and invited investors to participate via webcast. ... 1, 2015 at 11.00 a.m. Eastern Time --> ... 1, 2015 at 11.00 a.m. Eastern Time --> ... NY      Tuesday, December 1, 2015 at 11.00 ...
(Date:11/24/2015)... Nov. 24, 2015 /PRNewswire/ - Aeterna Zentaris Inc. (NASDAQ: ... on behalf of the Toronto Stock Exchange, confirms that ... are no corporate developments that would cause the recent ... --> --> About Aeterna Zentaris Inc. ... --> Aeterna Zentaris is a specialty biopharmaceutical ...
(Date:11/24/2015)... , November 24, 2015 SHPG ) announced ... in the Piper Jaffray 27 th Annual Healthcare Conference in ... 1, 2015, at 8:30 a.m. EST (1:30 p.m. GMT). --> ... Financial Officer, will participate in the Piper Jaffray 27 th ... NY on Tuesday, December 1, 2015, at 8:30 a.m. EST (1:30 ...
(Date:11/24/2015)... ... 24, 2015 , ... In harsh industrial processes, the safety ... sensors can represent a weak spot where leaking process media is a possible ... housings , which are designed to tolerate extreme process conditions. They combine rugged ...
Breaking Biology Technology: