Crabs
Guides
Grapsidae
shore crabs, marsh crabs, talon crabs
The Grapsidae are a family of crabs commonly known as shore crabs, marsh crabs, or talon crabs. The family's monophyly remains unconfirmed, with some taxa potentially belonging to other families. The family currently comprises ten genera and approximately forty species, including two fossil genera. Members occupy diverse coastal habitats ranging from rocky intertidal zones to pelagic environments.
Ocypodidae
Ghost and Fiddler Crabs
Ocypodidae is a family of semiterrestrial crabs comprising approximately 180 described species across 13 extant genera. The family includes two well-known groups: ghost crabs (genus Ocypode) and fiddler crabs (multiple genera including Leptuca and Minuca), plus the mangrove crabs of genus Ucides. Members are characterized by markedly unequal chelipeds in males, with the larger cheliped always exceeding carapace length. The family underwent substantial taxonomic revision in 2016, when the genus Uca was divided into 13 separate genera.
Panopeidae
mud crabs
Panopeidae is a family of true crabs comprising 26 genera of free-living species commonly known as mud crabs. Centers of diversity are the Atlantic Ocean and eastern Pacific Ocean, with most species inhabiting soft-bottomed marine environments. The family exhibits extensive morphological convergence among genera due to similar habitat and dietary preferences. Several species have been documented as invasive, including Dyspanopeus sayi, which has spread from North America to European and Black Sea waters.
Pilumnidae
Pilumnidae is a family of crabs in the superfamily Pilumnoidea, characterized by free articulation of all segments of the male abdomen and distinctive gonopod morphology. Members are common in tropical and subtropical intertidal and subtidal habitats, occurring on rocky substrates, coral rubble, and mud. The family has a broad geographic distribution across the Indo-West Pacific, western Atlantic, and other tropical regions, with species often associated with specific habitats such as mangrove mudflats, seagrass meadows, and continental shelf areas.
Randallia
Randallia is a genus of true crabs in the family Leucosiidae, established by Stimpson in 1857. The genus comprises approximately 17 described species. These crabs belong to the diverse brachyuran crab fauna and are classified within the subfamily Ebaliinae. Members of this genus are marine decapod crustaceans.
Xanthidae
mud crabs, pebble crabs, rubble crabs, gorilla crabs, round crabs
Xanthidae is a large family of true crabs commonly known as mud crabs, pebble crabs, rubble crabs, or gorilla crabs. Members of this family are frequently brightly colored and many species are highly poisonous, containing potent neurotoxins similar to tetrodotoxin and saxitoxin that are not destroyed by cooking. The family represents one of the most species-rich crab families, though many former members have been reclassified to other families. Some species exhibit distinctive behaviors such as anemone-carrying, which originated in the Eocene epoch approximately 40 million years ago.