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.
The Ocypodidae are a family of semiterrestrial crabs that includes the ghost crabs and fiddler crabs. They are found on tropical and temperate shorelines around the world.
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.
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:
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.
Inachidae is a family of crabs, containing 39 genera:
Leucosiidae is a family of crabs containing three subfamilies and a number of genera incertae sedis:
Micropanope is a genus of crabs in the family Pseudorhombilidae, containing one exclusively fossil species and the following species:
Paraxanthias is a genus of crabs in the family Xanthidae, containing one exclusively fossil species and the following extant species:
Xanthodius is a genus of crabs in the family Xanthidae, containing one exclusively fossil species and the following species:
Pandalus is a genus of shrimp in the family Pandalidae. Members of the genus are medium-sized and live on or near the seabed. Some species are the subject of commercial fisheries and are caught by trawling. One species, Pandalus montagui, lives in association with the reef-building polychaete worm, Sabellaria spinulosa.
Sicyonia is a genus of prawns, placed in its own family, Sicyoniidae. It differs from other prawns in that the last three pairs of its pleopods are uniramous, rather than biramous as seen in all other prawns.
Crangon is a genus of shrimp.
Cyclograpsus is a genus of crabs, containing the following species:
Blepharipodidae is a family of sand crabs (Hippoidea), comprising the two genera Blepharipoda and Lophomastix. They are distinguished from the other families in the superfamily Hippoidea by the form of the gills, which are trichobranchiate (filamentous) in Blepharipodidae, but phyllobranchiate (lamellar) in Albuneidae and Hippidae. Fossils belonging to the genus Lophomastix have been found in rocks dating back to the Eocene.
Rochinia is a genus of crab in the family Epialtidae, containing the following species:
The Camptandriidae are a family of crabs, with 38 species in 21 genera:
