Drilling predation on juvenile and adult gastropod shells during the Pliocene in the eastern Pacific, southern Mexico

Abstract

Quantifying the effects of drilling predation on juvenile and adult gastropods is important for understanding the paleoecology of communities. Although numerous studies have examined predation on adult shells, virtually no reports cover juvenile specimens. We compare predation frequency and prey effectiveness between juvenile and adult gastropods in a Pliocene assemblage from the eastern Pacific of Mexico. Evidence of predation in the sample was confirmed by the presence of drilling in the shells, ascribed to Oichnus simplex Bromley, 1981 and O. paraboloides Bromley, 1981, which showed active predation by caenogastropods. The occurrence of drilling gastropods in the same locality reveals the possible predators as naticids (Polinices intermeratus (Philippi, 1853), and Natica broderipiana Récluz, 1844) and muricids (Eupleura vokesorum Herbert, 2005 and Thypina sp.). Some differences were found in predatory patterns between drilling gastropods, naticids drilled at a higher frequency than muricids in adults, while the opposite occurs in juveniles. Prey Effectiveness (PE) values were 0.00 for juveniles and 0.02 for adults.