Chemosensory basis of feeding behavior in pacific white shrimp, Litopenaeus vannamei Dana Eap, Sara Correa, Hanh Ngo-Vu, and Charles D Derby Neuroscience Institute, Georgia State University, Atlanta The Pacific white shrimp, Litopenaeus vannamei, is important as the principal species in the worldwide aquaculture of shrimp. It has also become a model in the study of crustacean biology, especially since it is one of the first decapod crustaceans to have its genome sequenced. This study examined an aspect of the sensory biology of these shrimp that is important in their aquaculture, by describing their peripheral chemical sensors and how they are used in acquiring and consuming food pellets. We used scanning electron microscopy to describe the diversity of sensilla on the shrimp’s major chemosensory organs – antennules, antennae, mouthparts, and legs. We then explored the roles that these chemosensory organs play in the shrimp’s search for, acquisition, and ingestion of food pellets, using behavioral studies on animals with selective sensory ablations. We found that the antennules mediate odor-activated searching for pellets, with both the lateral and medial antennular flagella contributing to this behavior and thus demonstrating that both aesthetasc (olfactory) and distributed chemosensors on the antennules can mediate this behavior. Once the shrimp finds and grasps the food pellet, the antennular chemoreceptors no longer play a role, and now the chemoreceptors on the mouthparts and legs control ingestion of the pellets. This sequence of chemosensory control of feeding in L. vannamei, a dendrobranchiate crustacean with small antennules and an ability to live and feed in both benthic and pelagic environments, is generally similar to that of the better studied, large-antennuled, benthic reptantian crustaceans including spiny lobsters, clawed lobsters and crayfish, and crabs.