Shell remodeling in response to increased risk of predation in a marine snail

Biomineralized structures in animals can undergo remodeling, altering the original construction of the structure. Remodeling such structures could enhance plastic inducible defenses and mitigate some hypothesized limits to adaptive phenotypic plasticity. Predator-induced shell thickening in marine snails, already a model for studies of adaptive plasticity, provides a potentially good system to study the role of hardened structure remodeling for enhancing the adaptive value of phenotypically plastic responses. However, studies on predator-induced shell plasticity tend to examine only recent shell growth, and plastic remodeling of older regions of the shell has been previously unexplored. Therefore, we examined the potential for shell remodeling by the marine snail Nucella lamellosa in response to its major predator, the shell-breaking predatory crab Cancer productus. For snails exposed to chemical cues from C. productus, shell thickness and microstructure in the newest parts of the shell differed from controls. In response to chemical cues from C. productus, snails also remodeled older parts of the shell, producing overall thicker shells toward the apex compared to controls. This predator-induced shell remodeling may provide a new model for examining inducible defenses and the role of reversibility and epi-phenotype limits to adaptive phenotypic plasticity.