<P> Movement both horizontally and vertically in response to light and dark as well as temperatures have been observed, but over a short timespan the movement seems to be random . </P> <P> Experiments seem to indicated that the snail responds to light and current, and moves accordingly . </P> <P> L. littorea is an omnivorous, grazing intertidal gastropod . It is primarily an algae grazer, but it will feed on small invertebrates such as barnacle larvae . It uses its radula to scrape algae from rocks and, in the salt marsh community, pick up algae from cord grass or from the biofilm that covers the surface of mud in estuaries or bays . Macroalgae that are readily consumed include Ulva lactuca and Ulva intestinalis; if provided, blue mussel also seems to be eaten . </P> <P> The radula is taenioglossate, consisting of seven teeth per row: one middle tooth, flanked on each side by one lateral and two marginal teeth . The radula is used to scrape algae and detritus . </P>

How to take care of a periwinkle snail