Guardian: Slicker snails stick to the trail
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 fresh 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…
The long trails of mucus left behind by snails have multiple roles. "Most snails are pretty blind - in complex habitats where visual tracking might be difficult, following a mucus trail might be a handy thing to do," said Dr Davies. "In the marine environment, the trails can act as a trap for food the snail might like to eat, because the mucus is sticky."
Snails also know if a mucus trail is their own and can detect the sex of snails that have laid other trails. "It's handy if you want to follow a trail to mate with another snail," said Dr Davies.
If snails expend so much energy making mucus, I wonder if they might also eat some of the mucus from the trails they follow, in the same way that some spiders eat their own silk, some snakes their own shedded skin, and some mammals their own afterbirth. It would seem to be an efficient way of getting the right sort of nutrients they would need to make their mucus.
(Not that I know anything about snails, you understand.)