Multimodal communication in crayfish: sex recognition during mate search by male Austropotamobius pallipes

The role of multiple signals in sex recognition in the crayfish Austropotamobius pallipes was investigated by analyzing the main channels (chemical or chemical plus visual) used by males during mate search. The behavioral responses of males were recorded when they were exposed to four different treatments: female odor only, male odor only, female odor plus visual cues, and male odor plus visual cues. Males did not respond to chemical cues alone emitted by a female, but required both chemical and visual stimuli. The high-flow conditions of the aquatic habitat occupied, the restricted mating period, and the low density of the population examined may explain the use of both cues in sex recognition by males.