VAUGHN, D.; University of Washington: The Ballad of the Veliger Revisited: How larval interactions potentially modify the behavior, morphology and life history of a marine gastropod.
In 1929, Walter Garstang considered �predaceous foes� and the tactics of their planktonic prey, larval gastropods, which can retract into their shells and sink upon contact with potential predators. Garstang�s observations suggested that induced behavior, coupled with the armor of a larval shell, disrupts predation. While assessing and responding to predators is well documented in adult marine invertebrates and manifested in changes in morphology, behavior and life histories, it has been unclear whether the larvae of marine organisms display a similar range of plastic responses to predation. This study of the planktonic larvae of the intertidal snail Littorina scutulata presents preliminary results suggesting that gastropod veligers are capable of responding to actual and perceived predation through induced changes in behavior and shell morphology. Observations of laboratory reared veligers and Cancer sp. zoea larvae demonstrate that zoeas are aggressive, and occasionally successful, predators on veligers. Limited direct contact between zoea and veligers does not produce a consistent behavioral response, but does result in a significantly rounder shell morphology. Experimental veligers reared in water following interactions between veligers and Cancer sp. megalopae, as well as between L. scutulata and Cancer oregonesis adults, also demonstrate significant changes in larval shell shape. In each treatment, veligers developed a rounder shell than control veligers. Although it is unknown whether this predator-induced shell shape is adaptive, or what consequences this morphological change has following metamorphosis, these data suggest that some marine larvae are capable of developing predator-induced morphologies and contributes to our understanding of how natural selection operates throughout the development of organisms characterized by complex life histories.
