gastropods and bivalves, show phenotypicplasticity in their shell morphology in response to predation risk (Appleton & Palmer1988, Trussell & Smith 2000, Bourdeau 2010). Predation can therefore act as adirectional gastropods and bivalves, exhibit phenotypic plasticity in their shell morphology in response to predation risk. Predation can act as a directional selection pressure, resulting in specific prey phenotypes, such