Meeting Abstract

P2.127  Jan. 5  Induced plasticity and shell strength in the intertidal snail Nucella ostrina PEARSON, E. L.; University of California, Davis (Current address: University of Redlands) ed_pearson@redlands.edu

Phenotypic plasticity of the shells of molluscs is often induced by the presence of water-borne cues originating from predators, typically durophagous decapod crustaceans native to the range of the experimental molluscs. However, control treatments in most previous experiments have not included non-predatory decapod species as potential induction cues, nor have they included the scent of injured conspecifics without any contemporaneous predator scents. Here, I exposed an intertidal gastropod, Nucella ostrina, to one of seven treatments: a raw sea water control; the scent of injured N. ostrina without any crab scent; and the scent of one of five decapod species (two brachyurans native to much of the range of N. ostrina, a recently introduced brachyuran, and two anomuran species; all fed other N. ostrina). The results indicate that, as in many other molluscan species, these snails do respond to the scent of native predatory crabs by thickening their shells, but they also respond to a recently introduced predator, and even non-predatory decapods. Also, while phenotypic plasticity is due, in part, to the scent of injured conspecifics, the response by N. ostrina to the combination of decapods and injured conspecifics is significantly greater than their response to injured conspecifics alone. Mechanical tests on shells from N. ostrina exposed to these experimental conditions also demonstrate that the phenotypic response by N. ostrina to decapods increases the crushing resistance of their shells. However, the addition of shell material, rather than a change in the material properties or the architecture of the shell, appears to be responsible for most (if not all) of this increased shell strength.