Chiridotea caeca dwells in the intertidal zone of sandy beaches where it is shown for the first time to be a predator of sympatric benthic fauna. Laboratory feeding experiments revealed that C. caeca captured and consumed the haustoriid amphipod Amphiporeia virginiana and the polychaetes Scolelepis squamata and Neanthes succinea (an estuarine polychaete). Prey were captured with the first pair of pereopods (gnathopods), often torn and then pressed against the mouthparts where trituration took place prior to ingestion. Examination of the hindgut contents of 539 isopods (immatures and adults) showed that prey consisted primarily of crustaceans (haustoriid amphipods, young-of-the-year Emerita talpoida) and occasionally polychaetes and insects. Mancae were cannibalized in the laboratory. This study indicates that Chiridotea caeca competes with other predators (fishes, shorebirds, various invertebrates) for benthic prey within the surf zone.