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.
Majidae is a family of crabs, comprising around 200 marine species inside 52 genera, with a carapace that is longer than it is broad, and which forms a point at the front. The legs can be very long in some species, leading to the name "spider crab". The exoskeleton is covered with bristles to which the crab attaches algae and other items to act as camouflage.
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.
Maja is a genus of majid crabs erected by Jean-Baptiste Lamarck in 1801. It includes the following extant species:
Parthenopidae is a family of crabs, placed in its own superfamily, Parthenopoidea. It comprises nearly 40 genera, divided into two subfamilies, with three genera incertae sedis:
Callianassa is a genus of mud shrimps, in the family Callianassidae. Three of the species in this genus have been split off into a new genus, Pestarella, while others such as Callianassa filholi have been moved to Biffarius. The genus is named after the Nereid of the Greco-Roman mythology.
Palaemon is a genus of caridean shrimp in the family Palaemonidae.
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.
Macropodia is a genus of crabs, belonging to the family Inachidae. It contains the following species:
Epialtinae is a subfamily of crabs, containing the following genera:
Leucosiidae is a family of crabs containing three subfamilies and a number of genera incertae sedis:
Pilumnus is a genus of crabs, containing the following species:
Pisinae is a subfamily of crabs in the family Epialtidae, comprising the following genera:
Achaeus is a genus of crabs comprising the following species:
Hyastenus is a genus of crabs in the family Epialtidae, subfamily Pisinae, containing the following extant 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:
Geryonidae is a family of crabs, including the following subfamilies and genera:
