Leptuca pugilator (Fiddler crabs) also called Atlantic sand fiddler crab or calling crab are decapod crustaceans belong to the Uca family. They are part of the Ocypodidae family of brachyuran crabs, the most recent aquatic creatures to have reached the shore. More than 100 species of fiddler crab make up 11 of the 13 genera in the Ocypodidae crab family. These species are present in coasts of the sea and brackish intertidal mud flats, lagoons and swamps, mangroves, salt marshes and sandy or muddy coasts of West Africa, the Western Atlantic, the Eastern Pacific, the Indo-Pacific and the Algarve regions of Portugal and fiddler crabs are readily recognised by their distinctively asymmetrical claws. Fiddler crabs are best known for their dimorphic claws. The most special feature of Uca pugilator is that it is capable of regenerating lost limbs. Uca pugilator are not only effective cordgrass regulators, but are also important to the food web. Fiddler crabs also promote the turnover and mineralisation of essential nutrients.In addition, many of the species-specific body colour patterns that can serve as signals intra-and inter-specific correspondence.