Xanthidae is a family of crabs known as gorilla crabs, mud crabs, pebble crabs or rubble crabs. Xanthid crabs are often brightly coloured and are highly poisonous, containing toxins which are not destroyed by cooking and for which no antidote is known. The toxins are similar to the tetrodotoxin and saxitoxin produced by puffer fish, and may be produced by bacteria in the genus Vibrio living in symbiosis with the crabs, mostly V. alginolyticus and V. parahaemolyticus.
Calappa is a genus of crabs known commonly as box crabs or shame-faced crabs. The name box crab comes from their distinctly bulky carapace, and the name shame-faced is from anthropomorphising the way the crab's chelae (claws) fold up and cover its face, as if it were hiding its face in shame.
Portunidae is a family of crabs which contains the swimming crabs. Its members include many well-known shoreline crabs, such as the blue crab and velvet crab. Two genera in the family are contrastingly named Scylla and Charybdis; the former contains the economically important species black crab and Scylla paramamosain.
Macrophthalmus is a genus of crabs which are widespread across the Indo-Pacific. It contains the following species : Species in this genus are often referred to as sentinel crabs.
Charybdis is a genus of swimming crabs in the family Portunidae. It is named after the monster Charybdis of Greek mythology.
Pinnotheridae is a family of tiny soft-bodied crabs that live commensally in the mantles of certain bivalve molluscs and the occasional large gastropod mollusc species in genera such as Strombus and Haliotis. Tunicotheres moseri is commensal with a tunicate. The earliest fossils attributable to the Pinnotheridae date from the Danian.
Maja is a genus of majid crabs erected by Jean-Baptiste Lamarck in 1801. It includes the following extant species:
Calappidae is a family of crabs containing 16 genera, of which 7 are only known as fossils:
Pilumnoidea is a superfamily of crabs, whose members were previously included in the Xanthoidea. The three families are unified by the free articulation of all the segments of the male crab's abdomen and by the form of the gonopods. The earliest fossils assigned to this group are of Eocene age.
Actumnus is a genus of crabs in the family Pilumnidae. Alongside the 28 extant species, it has a fossil record extending back into the Miocene.
Etisus is a genus of crabs, containing the following extant species:
Inachidae is a family of crabs, containing 39 genera:
Metapenaeopsis, the velvet shrimps, is a prawn genus in the family Penaeidae. It contains these species:
Leucosiidae is a family of crabs containing three subfamilies and a number of genera incertae sedis:
Hypocolpus is a genus of crabs in the family Xanthidae, containing the following species:
Pilumnus is a genus of crabs, containing the following species:
Achaeus is a genus of crabs comprising the following species:
Ebalia is a genus of crab in the family Leucosiidae.
Rochinia is a genus of crab in the family Epialtidae, containing the following species:
