Siri-azul is the Blue crab (Callinectes sapidus), one of the largest crabs in the Brazilian coast, reaching be over 15 cm wingspan. The last pair of legs is modified locomotion, functioning as oars. The Siri-azul can pinch very quickly, causing minor injuries. Habitat in muddy beaches, both shallow and deep, and may rise by streams that flow into the sea, with its abundant occurrence in brackish water. Feeds on debris and dead meat.Occurrence anywhere in the coast of Brazil, staying in marine waters when then migrate to estuary waters in search of protection and lower salinities, and estuaries.