BELANGER, RM*; MCDOWELL, KE; MOORE, PA; ZIELINSKI, BS; Bowling Green State University; University of Windsor; Bowling Green State University; University of Windsor: Reproductive significance and sensory hair morphology of the major chelae of male crayfish Orconectes rusticus

It has been shown that the major chelae of crayfish have both mechano- and chemosensory abilities (Bauer and Hatt 1980; Hatt and Bauer 1980; Altner et al. 1983). Our previous investigations have shown that reproductive male crayfish (Orconectes rusticus) use their major chelae and respond significantly with an increased handling time to a female conditioned water source when compared to those that have been sensory lesioned. We have also shown that reproductive males use their major chelae for handling a female odour source which differs from a food odour source, where they use their walking legs and maxillipeds. For this reason, it is important to investigate the morphology of the sensory hairs on the major chelae of male crayfish in order to identify which sensory hairs could be used for perception of female odours. Using scanning electron microscopy to visualize hair pockets on the dorsal surface of the chelae, we have shown an increase in sensory hair pockets and sensory hairs (simple and plumose setae) in reproductive males when compared to non-reproductive males. A permeability assay using crystal violet demonstrated that simple setae readily take-up and hold the dye after clearing with xylene, while plumose setae do not. Also, DiI and acetylated tubulin readily stain neural structures found within simple setae, suggesting that simple setae are putative chemoreceptors. To confirm this, transmission electron microscopy was used to determine the ultrastructure of simple and plumose setae. Overall we have found that simple setae on the chelae are putative chemoreceptors and thus may be used for perception of female odours. Future analysis will use electrophysiology to examine peripheral processing of female odours.