True Crabs (Brachyurans)
Family Dromiidae (Burrowing Crabs)
Family Calappidae (Box Crabs)
Family Matutidae (Moon Crabs)
Family Corystidae (Masked Burrowing Crabs)
Family Dorippidae (Sponge Crabs)
Family Menippidae (Stone Crab)
Family Oziidae (Forceps Crab)
Family Leucosiidae (Pebble Crabs)
Superfamily Majoidea (Spider Crabs)
Family Inachidae (Velcro Crab, etc)
Family Parthenopidae (Elbow Crabs)
Family Pilumnidae (Hairy Crabs)
Family Portunidae (Swimming Crabs, Flower Crabs, Mud Crabs)
Flower Crabs (Portunus pelagicus) are one of the crabs commonly sold in marketplaces. They have a distinctive "flowery" pattern on their shell. They are a type of Swimming Crab (Family Portunidae), which also includes the Mud Crabs used for chilli and pepper crab.
Moulted shell at Chek Jawa ©Tan KH
Mud Crabs (genus Scylla) are the type of crabs found on our dining table. Fortunately, the local mud crabs are not as large as the Giant mud crab (S. serrata), which is the one commonly used for chilli and pepper crabs. They belong to the family Portunidae (the swimming crabs). Singapore has three species: Orange (S. olivacea), Green (S. paramamosain) and Purple Mud Crab (S. traquebarica). The Orange Mud Crab has orange claws, the Green Mud Crab has green and orange claws, and the Purple Mud Crab has purple claws.
Family Sesarmidae (Sesarmine Crabs, Vinegar Crabs, etc)
Family Sesarmidae includes the tree-climbing crabs, which are commonly seen at Sungei Buloh.
The most easily recognised are the large Vinegar Crabs (Episesarma sp.). The Singapore Vinegar Crab (E. singaporense) has red claws; the Pink-fingered Vinegar Crab (E. chentongensis) has a pale movable claw and a red unmovable claw; the Violet Vinegar Crab (E. versicolor) has pale or violet claws.
Singapore Vinegar Crab (E. singaporense)
Pink-fingered Vinegar Crab (E. chentongensis)
Violet Vinegar Crab (E. versicolor)
Family Varunidae (Paddler Crabs, etc)
Superfamily Ocypodoidea (Stalk-eyed Crabs)
Family Dotillidae (Soldier Crabs, Sand Bubbler Crabs, etc)
Family Macrophthalmidae (Sentinel Crabs, etc)
Family Ocypodidae (Ghost Crabs and Fiddler Crabs)
Ghost Crabs (Genus Ocypode) belong to the same family (Family Ocypodidae) as the Fiddler Crabs (Genus Uca). They are so called because they are able to disappear quickly into their burrow when threatened. They are found on sandy coasts. Sometimes, they have one claw larger than the other, but the size difference is not as distinct as the fiddler crabs'. There are two species in Singapore - Horn-eyed Ghost Crabs (O. ceratophthalma) and Common Ghost Crab (O. cordimana).
Fiddler Crabs (Genus Uca) belong to the same family (Family Ocypodidae) as the Ghost Crabs (Genus Ocypode). The male is easily recognised by having a claw disproportionately larger than the other. The female has claws of the same size.
Porcelain Fiddler (U. annulipes)
U. dussumieri (probable)
U. hesperiae (probable)
Rosy Fiddler (U. rosea)
Purple Fiddler (U. paradussumieri)
U. perplexa (probable)
U. tetragonon (probable)
U. triangularis (probable)
Orange Fiddler (U. vocans)
Rosy Fiddler Crab (U. rosea)
Orange Fiddler Crab (U. vocans)
Male Orange Fiddler (U. vocans) at Chek Jawa ©Lau SY. Male and female Orange Fiddler (U. vocans) at Chek Jawa ©Tan KH
Hermit and Porcelain Crabs (Anomurans)
Family Coenobitidae (Land Hermit Crab)
Hermit Crabs use empty shells as shelters because they have a soft body.