Foraging behavior and prey selection of the leather seastar Dermasterias imbricata

Abstract

Stomach contents of 243 Dermasterias imbricata (Gmbe) from 2 field sites in Monterey Bay, central California (USA), revealed a diet consisting primarily of the corallimorphian anemone Corynactis califomica. A survey of potential prey species demonstrated that C. californica were found in 85 % of 52 randomly placed '/am2 quadrats and 96 % of 45 % m2 quadrats placed around D. irnbn'cata within our study area. All other species of anemones were either rare or absent from the study area, with the exception of a few large individuals. When presented with a choice between C. californica and Anthopleura elegantissima or A. xanthogrammica in the laboratory, D. imbricata consistently ate the Anthopleura spp. and avoided C. californica. In single prey presentations, A. elegantiss~maA, . xanthogrammica, and Metndium senile were all taken and consumed readily within the first day. In contrast, D. irnbricata presented with C. californica initially avoided this species, and 40 % of the D, imbricata did not feed within 3 d. This difference in selectivity appeared to be related to the anti-predator defenses of the varlous anemones. These results suggest that ecologists should be careful in employing terms such as 'specialist' or 'preferred prey item' without conducting controlled experiments on prey selection and examining behavioral interactions between predator and prey.