ABSTRACT: Predator-prey interactions often drive ecological patterns and are governed by factors including predator feeding rates, prey behavioral avoidance, and prey structural defenses. Invasive species can also play a large ecological role by disrupting food webs, driving local extinctions, and influencing evolutionary changes in prey defense mechanisms. This study documents a substantial reduction in the behavioral and morphological responses of multiple gastropod species (Nucella lapillus, N. ostrina, Urosalpinx cinerea) to an invasive predatory crab (green crab Carcinus maenas) under ocean acidification conditions. These results suggest that climate-related changes in ocean chemistry may diminish non-lethal effects of predators on prey responses including behavioral avoidance. While snails with varying shell mineralogies were similarly successful at deterring predation, those with primarily aragonitic shells were more susceptible to dissolution and erosion under high CO₂ conditions. The varying susceptibility to predation among species with similar ecological roles could indicate that the impacts of invasive species like green crabs could be modulated by the ability of native and invasive prey to withstand ocean acidification conditions.