Scylla serrata

Scylla serrata – Mud Crab

Habitat The mud crab inhabits muddy bottoms, mangrove marshes, and river mouths in estuarine environments.

Range It is native to the Indo-Pacific and has been introduced to Florida, Hawaii, and other areas. The introduction of this species to non-native areas was probably intentional in attempt to establish populations of this commercially valuable crab.

Description Also known as the serrated swimming crab, the mud crab is a robust crab belonging to the family of swimming crabs, Portunidae. These crabs are grayish green to purple brown and have small irregular white spots on the carapace and swimming legs. The carapace is smooth with strong transversal ridges and can exceed 18 cm in width. Males can have a maximum carapace width of 25-28 cm and a maximum weight of 2-3 kg. The gastric zone on the carapace is marked with a deep H-shaped groove.The carapace has four blunt frontal teeth. Each anterolateral margin on the carapace has nine similarly sized teeth. The chilipeds are robust and have several well developed spines. The rear legs are flattened into swimming appendages.

Ecological Notes Reproduction: The mud crab becomes sexually mature starting at around 90 mm in carapace width, usually within its first year of life. Males approach the females before the females have undergone a precopulatory molt and grasp them with their chelipeds and first pair of walking legs. They stay together for several days until the female molts. After molting, males initiate copulation and deliver non-motile spermatozoa that may be retained by the females for several weeks or months. The females lay clutches of up to 2 million eggs. Females carry their egg clutches on their pleopods, migrate offshore, and then the eggs will hatch in a few weeks.

Physical Tolerances: Hydrology - Adult Scylla serrata are broadly eurohaline, although individuals other than spawning females preferentially inhabit brackish inshore habitats.

Temperature - Adult and sub adult Scylla serrata are broadly eurythermal, while larvae exhibit a somewhat narrower tolerance.

Trophic Status - Mud crabs are mainly carnivorous and emerge at night to prey upon small invertebrates such as mollusks, crustaceans, and polychaetes. They do consume a small amount of detritus and plant material.

Personal Information Scylla serrata was found at Nags Head Sound in Dare County, North Carolina.

References Smithsonian Marine Station at Fort Pierce]Fisheries and Aquaculture Department] Department of Fisheries: Western Australia]

Additional Information Chen, L. L., Lo, C. F., Chiu, Y. L., Chang, C. F., & Kou, G. H. (2000). Natural and experimental infection of white spot syndrome virus (WSSV) in benthic larvae of mud crab Scylla serrata.Diseases of Aquatic Organisms, 40(2), 157-161.

White spot syndrome virus (WSSV) is the causative agent of white spot syndrome in shrimp, and has a wide range of hosts, including Scylla serrata. This study investigated the presence of WSSV in benthic larvae of the mud crab via polymerase chain reaction and in situ hybridization. It was discovered that 60% of the larvae were infected with WSSV. Histological and in situ hybridization data showed that WSSV tissue tropism in Scylla serrata larvae is similar to that found in shrimp.

Catacutan, M. R. (2002).Growth and body composition of juvenile mud crab, Scylla serrata, fed different dietary protein and lipid levels and protein to energy ratios.Aquaculture, 208(1), 113-123.

The mud crab, Scylla serrata, is farmed on a commercial scale in several tropical countries and their diet development is important. This study investigated the effect of different dietary protein and lipid levels and protein to energy ratios on growth and body composition of the mud crab, Scylla serrata. The results showed that Scylla serrata grew well when fed a diet containing 32-40% dietary protein with either 6% or 12% lipid at dietary energy ranging from 14.7-17.6 MJ/kg.

Contributed by Caitlin Duncan

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