MEAD, K. S.; BRUESTLE, A. E.; Denison University: Do Crayfish From Different Flow Environments Have Different Arrangements Of Chemosensors On Their Antennules?

Many aquatic crustaceans use water-borne chemical cues in ecologically critical activities such as finding food, mates, suitable habitat, detecting predators, and communicating with conspecifics. These chemical cues are often present as odor plumes, which consist of fine filaments containing high concentrations of odor molecules interspersed with the surrounding fluid. Several parameters affect the structure of an odor plume and thus how the plume is encountered by navigating animals. These include the size-scale of the bottom substrate and flow conditions such as the mean velocity, turbulence level, and the gradient of flow speed above the substratum. Several species of Ohio crayfish (Cambarus cavatus, C. robustus, C. thomai, Orconectes immunis, O. sanborni and O. virilis ) were collected from a variety of flow habitats, including streams with silt, sand, gravel, cobble, boulders, rock rubble in pools, spring-fed streams, and stagnant lakes. Some crayfish were exposed to primarily still or slow moving water, while others habitually experienced rapidly moving and/or turbulent flow. Since odor plume structure varies according to flow habitat, we hypothesized that crayfish antennules from species living in different flow environments would have different patterns of aesthetasc arrangements on their filaments, to best encounter odors in that habitat. We compared aesthetasc length and diameter, the ratio of the gap between aesthetasc rows to the aesthetasc diameter, and the number of antennular segments bearing aesthetascs among species. We measured most of these parameters at three positions along the antennule and on at least three individuals per species. We found effects of both flow and antennule position on aesthetasc structure and arrangement.