Research has shown that the major chelae of male crayfish, Orconectes rusticus, are important chemosensory appendages and may aid in the perception and discrimination of female odours. However, it is unclear whether the major chelae are important for localization of female odour sources. In this study, we examined the role of sensory information from the major chelae in the localization and discrimination of conspecific female odours. We analysed the behavioural reactions of form I male crayfish to two different odour treatments: reproductive female-conditioned water or water (controls) delivered from one end of a test arena. Also, all male crayfish either had their chelae intact or sensory blocked. We measured locomotory behaviours in response to odours and chelae treatments. In addition, behaviours performed at the source of the odour were quantified. Male crayfish with intact chelae spent more time closer to a reproductive female odour source, whereas crayfish with blocked chelae showed no preference. There was no response to water. Male crayfish demonstrated differences in chelae waving and other local behaviours in response to female odours. These results suggest that the major chelae are important sensory structures, which aid in the localization and discrimination of female odours.
Available at: http://works.bepress.com/paul_moore/6/