An important part of quantifying predator-prey dynamics is to understand the contribution of various prey types to the predator diet. Although the role of juvenile penaeid shrimp as benthic predators is well established, recent research has indicated that penaeids are also capable of utilizing the energy available in zooplanktonic form. Yet the relative role of juvenile penaeids as direct zooplankton predators, capturing and consuming zooplankton from the water column—as compared with their role as benthic predators of animals that live on, or have fallen to, the bottom remains unknown. Two separate sets of laboratory experiments were conducted to determine the density-dependent predation rates of juvenile Litopenaeus setiferus feeding directly on (1) zooplanktonic prey Artemia salina in the water column and (2) benthic prey Mercenaria mercenaria in sediment. The average proportional mortalities for M. mercenaria (43% to 97%) were much higher than for A. salina (−10% to 28%). At low prey densities, proportional prey mortality increased with increasing prey densities for both M. mercenaria and A. salina, indicating a type III functional response by L. setiferus. A maximum consumption rate of 476 M. mercenaria/L. setiferus/hr was estimated in the benthic feeding experiments, whereas predator satiation was not observed even at the highest A. salina densities. High proportional M. mercenaria mortalities across moderate densities (1,000–2,500 m⁻²) suggest the potential for L. setiferus regulation of Mercenaria populations. Negative proportional A. salina mortalities at low and moderate densities suggest that L. setiferus are not efficient zooplankton predators. The variable consumption rates displayed by L. setiferus feeding on different prey types are a demonstration of their dietary plasticity as omnivores. Although L. setiferus are more effective as benthic predators, their ability to capture and consume prey from the water column suggests that zooplankton may be a viable alternative prey source when benthos are unavailable or inaccessible.