Predator-induced Morphologies and Cue Specificity in Veliger Larvae of Littorina Scutulata

Examples of phenotypic plasticity are well documented, especially in the context of predator-prey interactions. However, evidence of inducible defenses is scarce in marine larvae. In order to better understand morphological plasticity in the larvae of the gastropod Littorina scutulata, we exposed veligers to predatory zoeae of Hemigrapsus nudus. The treatments included growing veliger larvae in the presence of predators and growing veliger larvae in the presence of predators consuming conspecific veliger larvae. When compared to controls in seawater, veligers developed rounder shells, smaller apertures, and thicker apertural margins in response to the presence of predators. In the presence of predators consuming conspecific veliger larvae, veligers formed smaller apertures and the thickest shell margins, but the shell shape was not significantly different from control veligers. The different responses to different treatments with planktonic predators indicate that larvae can vary shell characteristics and may indicate a trade-off reflective of cue-specific defenses indicative of risk. The induced defenses resulted in enhanced survival of veligers exposed to predators. The use of a different species of predatory crab zoeae and measurement of an additional shell response variable validates and broadens an earlier report of inducible phenotypic plasticity in gastropod veliger larvae (Vaughn 2007; Ecology 88:1030-1039).