A seaside snail crawling along the gooey streak left by another snail is saving a lot of energy, say researchers, because it doesn't have to ooze so much slime itself.
Scientists have observed various kinds of snails following each others' paths, says Mark S. Davies of the University of Sunderland in England. Now, he proposes that followers are economizing on mucus. Davies and his colleague Janine Blackwell have measured the thickness of new and re-used trails of a common periwinkle (Littorina littorea), which creeps along rocky Atlantic shores. Following a fresh trail, it secretes much less slime than it expends when laying a new trail, the researchers report in a paper now online for an upcoming Proceedings of the Royal Society B.
"It's much, much more expensive to go around on a carpet of mucus than to run, walk, swim, or fly," Davies says. He has calculated that a periwinkle use