Uca pugilator, the sand fiddler crab is a species of fiddler crab that is found from Massachusetts to the Gulf of Mexico. It lives in burrows in coastal and estuarine mud-flats, and can be extremely abundant. It can be differentiated from its congeners U. pugnax and U. minax by the smoothness of the inside of its claws. One claw is larger than the other, and can be much larger than the crab's body, at up to 41 mm (1.6 in) long.