Alok Jha

LONDON: Snails that follow the slime trails left by others do it to save their strength, according to scientists. By using trails already on the ground, they can save two-thirds of the energy they use in making trails of their own.

Snails use a third of the energy from the food they eat on making the mucus needed to move around. "It's ridiculous if we spent a third of our energy just walking around, we wouldn't get very far," said Mark Davies, of the natural and social sciences department at the University of Sunderland, U.K.

"It's an inefficient way of getting around and it's very much more [energy] expensive than any other form of locomotion swimming, flying or walking. It's probably why these snails don't get very far."

He wondered whether snails might save themselves a lot of energy by using trails already on the ground. By watching Littorina littorea, a marine snail, crawl across microscope slides, Dr. Davies' research team calculated the amount of mucus produced by the gastropods as they wandered along their own trails and those of others. "Lo and behold, we found that the tracker snails produce significantly less mucus than the marker snails so they save quite a lot of energy."

The results were published in the Proceedings of the Royal Society.

Guardian Newspapers Limited 2007

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