Researchers have built a robot crab that can compete in claw-waving displays with real fiddler crabs, but "Wavy Dave" doesn't always come out unscathed.

Armed with a 3D-printed crustacean chassis and an ego the size of its oversized claw, Wavy Dave strutted onto the mudflats of Portugal like a tiny silicon Travolta. His goal: wiggle that one stupidly large claw at passing lady crabs while avoiding a crustacean-style beatdown from the dude crabs.