Mud Crab

Carapace smooth, with strong transversal ridges. Gastric zone on the carapace with a deep H-shaped groove. Front with 4 broad lobes, all more or less in line with each other; 9 broad teeeth on each anterolateral margin, all them with similar size and projecting obliquely outwards. Strong chelipeds with well developed spines on the outer surface of carpus and on the anterior and posterior dorsal parts of propodus. Carapace green to almost black with legs that may be marbled.

Indo-West Pacific: From East and South Africa to southeast and east Asia (from SE of China and Sri Lanka), and Northeast Australia. Also eastern around the Marianas, Fidji and Samoa Islands. Introduced in the Hawaii Archipielago.

Maximum carapace width: males between 25 to 28 cm (maximum weight between 2 and 3 kg).

In soft muddy bottoms where it dig deep burrows. Migrations offshore (up to 50 km) to spawn. Diet based on molluscs (bivalves: Mytilidae, gastropods) and crustaceans (grapsid crabs), rarelly on plant material and fish.Adults remain buried at day, emerging at sunset and night to feed.

Collected mainly by trawling, and using traps, baited wire mesh pots, hooking and by hand. From 1990 to 1995 yearly catches for Scylla serrata from the Western Central Pacific ranged from 5 960 to 12 882 t (FAO yearbook of fishery statistics). These catches include, however, the 4 species of Scylla recognized (see remarks). Therefore, Scylla olivacea is probably the most common species in many markets of Southeast Asia. In Australia the fishery for S. serrata and S. olivacea reached 700 t collected between 1989 to 1990. The existing catch and management practices, currently applied to a single species (S. serrata), have to be revised. The total catch reported for this species to FAO for 1999 was 13 431 t. The countries with the largest catches were Indonesia (8 560 t) and Thailand (3 050 t). The species is marketed alive. Some attempts to culture this species have been made.