Differences between two physid species (Gastropoda: Physidae) in antipredator behaviour induced by leeches

The occurrence and the intensity of specific behavioural defensive reactions were investigated in freshwater snails of the family Physidae, which vigorously shake their shells when attacked by invertebrate predators. Physella acuta and Physa fontinalis were exposed to two species of leeches with different hunting strategies—the molluscivorous Glossiphonia complanata and the opportunistic predator Erpobdella octoculata. Parameters of reaction were measured and compared between snails and leeches. Significant differences were found in the reactions of both snail species in 10 out of 11 measured parameters. Physa fontinalis reacted more intensively, with a higher number of shell movements triggered by both leech species. The study showed possible recognition by the prey of the predator species, followed by a specific defensive reaction. In general, G. complanata elicited more intensive reactions, especially in treatment with P. fontinalis.