Meeting Abstract
Snapping claws, which occur in both alpheid and palaemonid shrimps, are spectacular offensive weapons that create intense cracking sounds and shockwaves toward prey and opponents. True snapping involves: a) rapid claw closure facilitated by an energy storing mechanism at the joint, b) creation of a cavitation bubble, and c) destructive shock waves induced by cavitation bubble collapse. How such an extraordinary weapon evolved from ordinary pinching claws is not known. We examined claw form in over 100 species of caridean shrimp including several snapping taxa using modern visualization techniques (e.g., micro-CT, confocal microscopy). This survey revealed a unique type of energy storage mechanism in the snapping claw of basal Alpheidae and Palaemonidae: a “slip-and-cock system” similar in form to the “slipjoint” widely shared by non-snapping caridean shrimp. To assess the relation between form and function we conducted physical experiments using enlarged, 3D printed scale models of different claw types. These experiments revealed a minute yet functionally significant quantitative difference in joint structure that clearly demarcates pinching from snapping claw function. This previously unrecognized slipjoint in non-snapping caridean shrimp claws appears to be an evolutionary precondition for the subsequent evolution of spectacular snapping claws.
