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Shore-Level Size Gradients In Tegula Funebralis (A. Adams) : Seasonal Changes Influenced By Interaction Of Predator Preference And Prey Behavior, Daniel Victor Markowitz

University of the Pacific Theses and Dissertations

Aspects of the Pisaster-Tegula interaction are re-examined. Reproductive portions of T. funebrallis populations are shown to be immune to seastar predation through a combination of predator preference for larger snails and a withdrawal behavior that favors the escape of smaller snails after capture by a seastar . Experimental addition of p. ochraaceus in winter causes changes in the intertidal distribution of T. funebralis similar to those observed during the summer increase in seastar numbers. It is suggested that these results supplant the hypothesis that lowered prereproductive mortality influences formation and maintenance of vertical size gradients in the lower intertidal .