Two species of fiddler crab show no cost of bearing a sexually selected giant claw in predator escape behaviors

摘要

Male fiddler crabs possess one giant major claw, used for display and intermale combat. Comprising greater than 30% of body mass, the major claw is presumed to interfere with escape from predators by affecting balance during the righting response if the male is upended. We determined cost of the major claw and posterior legs for righting after the crab was upended in a simulated attack. In Leptuca pugilator and Minuca pugnax, males without major claws showed no difference in their righting time compared to individuals bearing major claws, but males lacking rear legs took significantly longer to right relative to intact males. The lack of cost of the major cheliped for righting time reinforces a previously determined lack of cost of the major claw in sprint speed, another measure important for escape. While the rear legs are crucial for righting, the massive claw imposes no cost to this vital response.