Jimmy McCloskey Variation in olfactory chemosensor morphology related to body size and sex in the crayfish Orconectes immunis. Division Sciences Department Biology Year 2004 Advisor Kristina Mead

Crayfish use water-borne cues to interpret their chemical environment. Cues from "distant" sources are sampled using olfaction chemosensors called aesthetascs on the antennules. The arrangement and shape of these chemosensors affect how much odor-containing fluid is able to penetrate close to the antennules during odor sampling. Crayfish of different sizes and sexes have different olfactory needs. This study hypothesizes that olfactory chemosensor structure may change as a function of animal size and gender.  The antennules of male and female Orconectes immunis were harvested and analyzed using Scanning Electron Microscopy. Scion Image software was used to measure several structural parameters including the number of aesthetascs bearing segments, aesthetasc length, diameter, insertion angle, and the distance between adjacent aesthetasc bundles.  Results showed several parameters varied as a function of size and revealed sexual dimorphisms within and across size classes.  There was also parameter variations related to the position along the antennule.