CLARK, A.J.*; JENSEN, J.S.; Univ. of Maryland, College Park; Univ. of Maryland, College Park: Feeding performance and prey selection of pile perch (Damalichthys vacca) on four species of Littorine snails

Pile perch (Damalichthys vacca) feed almost exclusively on hard-shelled invertebrates, using a highly developed pharyngeal jaw apparatus consisting of molariform toothplates and associated muscles. Among other hard-shelled prey, D. vacca are known to feed heavily on gastropods. Although there have been multiple studies on the morphological adaptations of D. vacca for durophagy, relatively little is known about their foraging behavior and ecology. This study focuses on the functional capabilities and feeding preference of D. vacca on four species of Littorine gastropods: Lacuna vincta, Lacuna variegata, Littorina scutulata, and Littorina sitkana. Feeding performance (handling time and crushing success) was compared for D. vacca feeding on all four gastropod species. In addition, relative prey preference was assessed for the two species of Lacuna, for L. variegata with and without attached egg masses, and for different size classes of L. vincta. At larger sizes, the Littorina species required greater handling times and were more difficult to crush than the Lacuna species. D. vacca showed no preference for L. vincta relative to L. variegata, and no preference for L. variegata with egg masses relative to those without egg masses. D. vacca were highly selective on prey size, with a highly significant (p<.0001) preference for larger L. vincta. Our findings suggest that there is no upper size refuge for Lacuna for this size class of D. vacca, however large Littorina may be able to escape predation.