Figure 1
From: Evolutionary variation in the mechanics of fiddler crab claws
Examples showing just a few of the divergent morphologies found in the fiddler crab major claw. ( A) Uca terpsichores has an elongated claw with gracile polex and dactyl, ( B ) Uca stylifera is a large, basal species, ( C ) Uca argolicola is a small species with a relatively short robust claw. During signaling, male crabs wave these claws in a species-specific pattern. During intra-sexual combat males interlock claws and apply force to a competitor’s manus using a dactyl or polex tubercle as indicated by arrows in frame (A).