Honest and dishonest signals of strength in Australian slender crayfish (Cherax dispar): are male's liars and cheaters?

Abstract

Cherax dispar. Crayfish routinely use their enlarged front claws (chelae) for both intimidation and fighting, making them an ideal system to examine the honesty of signals of fighting capacity. We evaluated five competing models relating morphological and physiological traits (body length, body condition, claw size, and claw strength) to dominance during paired competitive bouts. In an honest signaling system, claw size and strength will be good predictors of dominance during competitive interactions. We found females that possessed large chelae were more likely to possess stronger chelae and those individuals with stronger chelae were more likely to win competitive bouts, thus supporting current theory. In contrast, we found chelae strength of individual male C. dispar had no bearing on their dominance ability, indicating that displays of claw size were dishonest signals and the enlarged claws of males function more for intimidation than actual strength. Given the extent of bluffing among male C. dispar, it appears current theory underestimates the potential importance of dishonest signals in intraspecific animal communication.