Male-female communication in the crayfish Orconectes rusticus: The use of urinary signals in reproductive and non-reproductive pairings

Abstract

Animals use sensory communication to locate conspecifics, food, shelter, and avoid predators. Using urine visualization techniques as well as Digital Particle Illumination Velocimetry, we examined the role of urinary signals and current generations during social interactions of male and female crayfish. Both reproductive and non-reproductive crayfish were paired to gain a better understanding of how reproductive state influences communication. Analyses of agonistic and mating events were paired in time with recorded urine release and current generation, illustrating a correlation of chemical communication with ritualized social behavior. Four treatment groups were run with specific combinations of different reproductive status: (1) both opponents reproductively active, (2) only the male in reproductive, (3) only the female reproductive, or (4) both opponents non-reproductive. Results showed differences between treatment groups in urine release, current generation, and social behavior. Within reproductive pairings, both the male and female crayfish generated currents and released urine at higher rates than those in other treatment groups. Urine was released most often when opponents were in chelae contact with each other and these releases were often accompanied by anterior current generation. In addition, communication was different in reproductive trials where mating occurred. Overall, the results indicate that the use of hydrodynamic and chemical signals changes as a function of reproductive state and that this change in communication probably indicates readiness to mate. © 2007 The Authors.