Mimicking snails’ movement could lead to new propulsion methods

October 10th, 2008 - 3:49 pm ICT by IANS  

Washington, Oct 10 (IANS) A new mode of propulsion based on how snails create ripples of slime to crawl upside down beneath the surface has been propounded by a California University engineer. Eric Lauga, an assistant professor of mechanical and aerospace engineering at the University’s Jacobs School of Engineering, recently published a paper explaining how and why water snails can drag themselves across a fluid surface that they can’t even grip.

Based on Lauga’s research, the secret is in the slime. The main finding is that soft surfaces, such as the free surface of a pond or a lake, can be distorted by applying forces; these distortions can be exploited (by an animal, or in the lab) to generate propulsive forces and move.

Some freshwater and marine snails crawl by “hanging” from the water surface while secreting a trail of mucus. The snail’s foot wrinkles into little rippling waves, which produce corresponding waves in the mucus layer that it secretes between the foot and the air.

Parts of the mucus film get squeezed while other parts are stretched, creating a pressure that pushes the foot forward. Recent California Univeristy (CU), San Diego, research reveals that water snails release mucus as a means of transportation.

Lauga and his team demonstrate that water snails have to distort the surface in order to move. “If they don’t, they won’t go anywhere,” said Lauga, who explained that these water snails naturally rise due to their low weight, and therefore do not have to work to remain near the surface.

Lauga and his colleagues said their finding could lead to a new method of propulsion. One of Lauga’s colleagues, Anette Hosoi of the Massachusetts Institute of Technology, has already imitated the adhesive/lubricating propulsive method of land snails to drive a robotic device, according to a CU release.

Now, as a result of this new water snail finding, the researchers said it may be possible to build similar devices that walk on water. “The water snails show us that this is possible, and therefore one can design biomimetic systems taking advantage of that movement,” Lauga said.

This type of technology could be used for a number of small scale applications, such as aquatic military uses. “The military is always looking for new ways to navigate and control displacements,” he said.

“This is interesting from a pure biological standpoint because it helps us understand Mother Nature,” Lauga said.

These findings have been published in journal Physics of Fluid.

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