Inducible Morphological Defenses in Hooked Mussels, Ischadium recurvum: Response to Native and Non-native Crab Predators

Abstract

Inducible morphological defenses can be an important factor in predator prey interactions. While Hooked mussels, Ischadium recurvum, have been shown to exhibit inducible defenses in response to predators within their range, the ability of Hooked mussels to mount a defense against non-native predators has not been explored. In order to investigate the ability of Hooked mussels to mount an inducible defense response to novel predators, Hooked mussels were exposed (for two months) to the constant effluent of the native Blue crab, Callinectes sapidus, the non-native Green crab, Carcinus maenus, and were compared to mussels that were not exposed to any crab effluent. Mussels exposed to Blue crab effluent produced significantly (p < 0.05) more byssal threads compared to both Green crab exposed and control mussels. Green crab exposed and control mussels showed no differences in byssal thread production (p > 0.05). The lack of an inducible response in Green-crab exposed mussels suggests that crab induced byssal thread production is specific to native crab predators as well as the fact that Hooked mussels are incapable of recognizing novel predators by their effluent alone.