MCCLOSKEY, J. K.; MEAD, K. S.; Denison University; Denison University: How Do The Shape And Arrangement Of Crayfish Aesthetascs Vary With Body Size And Sex?

Many aquatic crustaceans use water-borne chemical cues to find food, mates, and suitable habitat, to detect predators, and to communicate with conspecifics. In crayfish, cues from these �distant� sources are sampled using chemosensors called aesthetascs on the antennules. The arrangement and shape of the chemosensors can affect how much odor-containing fluid is able to penetrate close to the chemosensors during olfactory sampling. We investigated the role of body size and sex in affecting the number and arrangement of aesthetascs on crayfish antennules by performing scanning electron microscopy on three males and three females in each of four size classes (30-40 mm, 40-50 mm, 50-65 mm, and 65-80 mm rostrum-telson length) of Orconectes immunis , a local pond-dwelling species. We used Image J to digitize several structural parameters, including antennule length, aesthetasc length, diameter, insertion angle, and the gaps between adjacent aesthetascs.