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.
Pinnotheres is a genus of crabs, including the pea crab. Many species formerly in Pinnotheres have been placed in new genera, such as Zaops ostreus, the oyster crab and Nepinnotheres novaezelandiae, the New Zealand pea crab. The species currently recognised in the genus Pinnotheres are:
Alpheus is a genus of snapping shrimp of the family Alpheidae. This genus contains in excess of 330 species, making this the most species-rich genus of shrimp. Like other snapping shrimp, the claws of Alpheus are asymmetrical, with one of the claws enlarged for making a popping noise. Some species in the genus enter into symbiotic relationships with gobiid fishes, and others associate with sea anemones.
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.
Charybdis is a genus of swimming crabs in the family Portunidae. It is named after the monster Charybdis of Greek mythology.
Upogebia is a genus of mud shrimp, in the family Upogebiidae, containing the following species:
Callianassidae is a family of ghost shrimp crustaceans belonging to the infraorder Axiidea, within the order Decapoda.
Pagurus is a genus of hermit crabs in the family Paguridae. Like other hermit crabs, their abdomen is not calcified and they use snail shells as protection. These marine decapod crustaceans are omnivorous, but mostly prey on small animals and scavenge carrion. Trigonocheirus and Pagurixus used to be considered subgenera of Pagurus, but the former is nowadays included in Orthopagurus, while the latter has been separated as a distinct genus.
Gilvossius is a genus of thalassinidean crustacean erected in 1992 from former members of the genus Callianassa. It is distinguished from Callianassa by the rounded, rather than squarish telson, and by the absence of the first two pleopods in males. The genus contains the following species:
Paguristes is a genus of hermit crab in the family Diogenidae. It includes the following species :
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.
Neotrypaea is a genus of ghost shrimp in the family Callianassidae, containing the following sixteen species:
Biffarius is a genus of ghost shrimp in the family Callianassidae, containing species formerly included in the genus Callianassa. Its members are small and generally live in the intertidal zone. In April 2020, a new species was described from the northeastern Brazilian coast. Biffarius was named in honour of Thomas A. Biffar, and includes the following species:
Lepidophthalmus is a genus of ghost shrimp.
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:
Ebalia is a genus of crab in the family Leucosiidae.
Daldorfia is a genus of parthenopid crab, belonging to the subfamily Daldorfiinae.
