Scallops respond to predators with a stereotypical swimming response which relies on jet propulsion, produced by repeated cycles of rapid opening and closing of their valves.Phasic muscle contractions, together with the muscular mantle, allow precise orientation of the jets of water and rapid displacement of the scallops.Two major groups of scallop predators, sea stars and crabs, use different strategies of attack.Sea stars are slow moving, non visual predators who use chemical and tactile receptors to locate prey.Crabs are fast-moving predators who can use visual capacities as well as sensory structures on the antennae and walking legs to locate scallops.Once the predators capture scallops, the attack mechanism is different, with starfish everting their stomach to digest and absorb the soft tissues whereas crabs use their claws to crush the shells and then feed on the soft tissues.Sea stars and gastropods are the predators most often reported to provoke swimming (Legault and Himmelman, 1993; Himmelman et al.2009), even though crustaceans are important predators on many scallop populations.