Phenotypic plasticity in response to environmental stimuli is exceedingly common across systems and taxa. For instance, predation risk in many gastropods can induce a variety of defenses including growing thicker shells, growing shells of different shapes, and developing apertural teeth. However, the role of coevolution between species that produce these defense responses and their consumers is not well known. This thesis examines the responses of an ovoviviparous gastropod (Littorina saxatilis) with low dispersal from three different habitats (marsh habitat, rocky habitat, and cobble stone habitat) to the presence of chemical cues from a native (Dyspanopeus sayi) and nonnative (Hemigrapsus sanguineus) crab predator. This work tested the potential role of coevolution in shaping phenotypically plastic responses, and whether responses to both a native and a nonnative predator differed for snails from different source sites. The morphological responses I tested for included axial growth, width growth, whorl growth, changes in total mass, and shell shape changes. I found that many measures of growth were needed in the investigation of plastic responses. Overall snails exposed to native predator cues had a similar response as those in the reduced diet treatment in both growth measurements and shell shape change, indicating a behavior response of reduced feeding in the presence of the native predator. Snails from the marsh and rocky habitats displayed a reduced response to cues from the nonnative predator, suggesting that they recognized this predator as a risk, but did not show as strong of a response as they did to the native predator. Snails in the rocky habitat, which live in barnacle tests, also had a slower growth rate than snails from the other two source sites. These results suggest the possibility of local adaptation and genetic differences between snails in these different source sites.