Derby, C.D., Department of Biology, Georgia State University, Atlanta, GA 30303, United States
Harpaz, S., Monell Chemical Senses Center, 3500 Market Street, Philadelphia, PA 19104, United States

1. 1. Chemoreceptor cells in the first pereiopods (legs) of the freshwater prawn, Macrobrachium rosenbergii, were investigated using single-unit, extracellular electrophysiological recording techniques on an isolated, perfused leg preparation. 2. 2. The cells were responsive to aqueous extracts of food (shrimp, mullet, trout chow), a salt mixture (artificial sea-water), amino acids (l-arginine HCl, taurine), a quaternary ammonium compound (betaine HCl) and ammonium chloride. 3. 3. The response specificity of individual cells ranged from narrow to broad, but on average was broad, being more similar to chemoreceptor cells of freshwater crayfish than of marine spiny or clawed lobsters. 4. 4. Responses were generally excitatory. However, some responses were inhibitory, the first such demonstration in aquatic crustaceans. 5. 5. These electrophysiological results highly correlate with results of feeding behavioral assays carried out on M. rosenbergii. © 1988.