There are various synonyms for the term "Genus Uca," which is a group of fiddler crabs consisting of around 100 species. Some of the commonly used synonyms for this genus include "Brachyura," "Cardisoma" and "Gelasimus." These distinctions are based on the variations in the size, color, and shape of the fiddler crabs. The genus Uca is found in intertidal regions across the world and known for their impressive claw display, which the males use for attracting females and communicating with other males. They are also important for their ecological role in maintaining the balance of the ecosystem and as a source of food for larger aquatic animals.