Snails that glide along existing mucus trails conserve up to 70 per cent of the energy they would otherwise use for locomotion.
Credit: Mark Davies
SYDNEY: Snails may be slow movers, but new research shows that they employ a cunning strategy to make massive energy savings.
Biologists at the University of Sunderland in England have discovered that some snails regularly follow mucus trails left by other snails, and save 70 per cent of the energy used to move around in the process.
Mucus has the benefit of acting like a kind of glue that allows slugs and snails to extend their habitats to the vertical and overhanging surfaces of plants. But mucus it is costly to produce and snails expend up to a third of all their resources on this unusual method of locomotion.
"This process is very taxing indeed - much more so than walking, swimming or flying," said study author Mark Davies. Therefore, any savings they make mean they have significantly more [energy] to put into breeding, feeding and evading predators.
Researchers had previously suggested that re-tracking existing mucus trails might help snails with limited vision navigate complex surfaces more easily and that gastropods might follow their own trials to find their way home.
To test the behaviour more rigorously, Davies and co-worker Janine Blackwell collected marine snails of the species Litorrina littorea from the U.K. seashore. The species is commonly found on the coasts of the East and West Atlantic. They allowed them to lay trails across arrays of microscope slides and followed their progress.
"Once a second snail went down the trail, we expected the trail to be twice as thick, but it wasn't - it was a lot less," said Davies. "Snails being able to save energy by trail following was totally unexpected."
Davies expects that most species of gastropods save energy in the same way, but that has yet to be tested.
This kind of finding about something that goes on every day in our own gardens, yet we haven't known anything about "illustrates how little we still know about the world around us," said Fred Wells, an expert on molluscs at the Western Australian Department of Fisheries in Perth.
Researchers have yet to understand how the snail's enigmatic method of locomotion might have evolved, he said.
The findings are detailed tomorrow in the British journal Proceedings of the Royal Society B.
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