Crassostrea virginica (American oyster) preys on:
microzooplankton
zooplankton
Ctenophora
Chrysaora quinquecirrha
Other suspension feeders
Mya arenaria
Crassostrea virginica
Polychaeta
Nereis
Macoma
meiofauna
Crustacea
Callinectes sapidus
Alosa sapidissima
Micropogonius undulatus

Based on studies in:
USA: Maryland, Chesapeake Bay (Estuarine)

This list may not be complete but is based on published studies.