Antennule ablation, sex discrimination, and mating behavior in the crayfish Procambarus clarkii

In order for the crayfish Procambarus clarkii to mate, each animal involved must identify the sex of the other. Crayfish are able to use chemoreception, mediated by the first antennae (antennules), as well as vision in sex identification. The relative importance of these two senses is not known; most work has centered on the use of the antennules. To assess the importance of antennules we studied mating in control pairs, in pairs where the females lacked antennules, in pairs where males lacked antennules, and in pairs where both lacked antennules. Ablation of antennules did not significantly affect the likelihood of mating or the delay before mating began. These findings demonstrate that P. clarkii can readily identify the sex of conspecifics without the use of their antennules. If the ability to identify sex had been impaired, one would expect mating to be less likely or to follow an unusually long delay. In addition, antennule ablation did not significantly affect the duration of mating. This stands in contrast to findings in the green crab Carcinus maenas, where the ablation of antennules in males leads to the substitution of multiple short matings for single long, continuous matings. It is concluded that P. clarkii can readily determine the sex of conspecifics without the use of the antennules and that the loss of antennules has no obvious effect on mating behavior.