Seasonal activity and foraging behaviour of the endangered limpet Patella ferruginea

Patellid limpets are herbivorous gastropod molluscs found on temperate rocky shores where they are often the dominant grazers. An analysis of their behavioural traits is crucial for an understanding of the dynamics of intertidal communities. Patella ferruginea, endemic to the Mediterranean, is the most endangered marine macro-invertebrate on the Western Mediterranean rocky shores and it is, currently, under serious risk of extinction. However, little is known about the biology of the species. Individuals forage almost exclusively during high tide through all seasons and types of tide. The species has not been significantly influenced by tides, whereas the season, their size and the day/night cycle do influencing their behaviour. Small individuals show significantly shorter foraging excursions and less extension of their foraging areas than do larger ones. The geometry of their foraging paths shows a very low incidence of trail following that could be a mechanism to avoid passing over previously grazed areas.