Snails' sense for survival revealed.
POND snails are able to sense chemicals released by their predators while they are still embryos in the egg, according to researchers at a Welsh university.
A study by Aberystwyth University in partnership with Exeter and Plymouth universities found that when snails were exposed to predator smell during their early developmental stage, they were better able to avoid predatory fish once they hatch.
Researchers said the "pre-programmed" response may be extremely important for snails to be able to survive just after hatching when they are very small and vulnerable.
To get an idea of how snails respond to predators, the team looked at how pond snails, or Lymnaea stagnalis, responded to smell from a predatory fish, tench.
The snails were exposed to predator smell throughout their embryonic development in egg capsules and once they hatched out, they were kept in a predatorfree environment for a week.
Tests showed that snails exposed to the predator smell as embryos strongly responded to the smell when they re-encountered it as juveniles, crawling out of the water to escape the potential predator.
Lead author Dr Sarah Dalesman, of Aberystwyth University, said; "We were quite surprised at how well the snails were able to learn during this very early phase of development.
"We also found embryos exposed to the predator smell hatched out at a smaller size than those kept in predator-free conditions."
Dr Simon Rundle, an academic at the University of Plymouth, added: "One of the most important findings in this study was that there appeared to be a genetic component to the snails' behaviour, with those animals whose grandparents had experienced fish predators in the wild showing the biggest response."