Washington, Oct 21 : In a new study, scientists have figured out the baffling method of propulsion of tiny aquatic snails, which makes them walk on water.
According to a report in National Geographic News, Eric Lauga, a professor of mechanical and aerospace engineering at the University of California, San Diego, led the study.
"How the snails were dragging themselves across a surface that they could not even grip was absolutely perplexing to us," said Lauga.
"Hanging on to the water's surface is not the issue for the snails. They are naturally buoyant, because they are so small," he added.
Even so, the snails need traction to move across the slippery surface.
By making small rippling motions with its foot, the snail creates traction for itself, Lauga and his colleagues found after studying videos of the snails.
"The snails' ability to move depends on water's tendency for its surface to resist disturbance. Water "wants" to stay flat," Lauga said.
When the snail ripples its foot, similar ripples are created on the water's surface. The ripples generate a downward force as the water flattens itself.
These ripples are just the right size for the snail to use to push itself along.
"If the ripples were too small, the snail would slip, as on ice," Lauga said. "If the ripples were too big, the snail could not 'grab' them," he added.
According to Howard Stone, a professor of engineering and applied mathematics at Harvard University, "I have seen other forms of fluid motion driven by surface undulations, but I do not recall having ever seen any study that demonstrated propulsion (like this) before."
"New insights on small- or large-scale propulsion open our minds to thinking about new ways to tackle problems. The mechanism shown in this paper as a means to propulsion is quite appealing," he added.
"It would be really interesting to build small-scale robotic versions of these snails to see if our understanding of their locomotion is correct and if we can recreate it," Lauga said.
While he doesn't see immediate practical applications for such devices, Launga said that, "in my wildest dreams, I can see James Bond releasing robotic snails on water to spy on his enemies."