The responses of South African patellid limpets to invertebrate predators
The starfish Marthasterias glacialis is a generalized predator, feeding particularly on Choromytilus meridionalis, but also on several limpets, notably Patella longicosta. Thais dubia (Gastropoda) feeds mainly on barnacles, mussels, and Patella granulans. The gastropods Burnupena delalandii and B. cincta are principally scavengers, feeding on damaged or dead animals. The responses of Patella spp. to these predators are described. P. granulans, P. concolor, P. compressa and P. miniata all retreat rapidly on contact. Small P. granatina and P. oculus respond similarly, but larger specimens react aggressively, smashing their shells downwards and often damaging the predator. The territorial species (P. longicosta, P. cochlear and P. tabularis) all retreat to their scars and remain clamped there. P. argenvillei and P. tabularis are usually unresponsive, possibly because they are too large to fall prey. Cellana capensis rolls its mantle upwards to cover the shell, preventing predators from attaching. The responses and their effectiveness are discussed in relation to other behavioural patterns displayed by limpets. There is no correlation between the intensity of a prey’s response to a predator and the degree of contact between the two in the field.