Scylla serrata (Forskål,1775)
The giant mud crab can reach a carapace width of 28 cm and a weight of 3 kg. Its carapace is smooth with clear cervical groove and 9 teeth lined in the margin, which is oval and pointed on both sides. Its pincers are stout, smooth and hairless, and four walking legs as wide and flat as swimming legs. Two distinct thorns lie on the half end of the external side of the pincer joint. For both males and females, pincers and swimming legs are clearly covered with a dark green meshwork pattern.
It is distributed over Japan, Ryukyu Islands, China, Taiwan, Southeast Asia, India, East Africa, South Africa, Australia, etc. They dwell in the estuaries as deep as 50 meters or intertidal mud flats in mangrove swamps. It is omnivorous, feeding on crustaceans, gastropods, bivalves, fish and crumbs. They mostly mate in spring and autumn, when females just shed their shells to expose their soft bodies that could be wrapped by walking legs of males for protection. In the past, the genus Scylla was considered to have only one species, Scylla serrate, but now it is sorted into four species, including Scylla olivacea, Scylla paramamosain, Scylla serrate and Scylla tranquebarica.
Due to its tasty meat and fast growth, it is highly valued. In Taiwan, it is called red crab, especially the female is highest priced with red, plump ovaries after mating. It is the favorite for foodies and a common food for folk cuisine.