Cryptochiridae is a family of crabs known commonly as gall crabs or coral gall crabs. They live inside dwellings in corals and cause the formation of galls in the coral structure.Johnsson, R., et al. (2006). The association of two gall crabs (Brachyura: Cryptochiridae) with the reef-building coral Siderastrea stellata Verrill, 1868. Hydrobiologia 559(1), 379-84.Kropp, R. K. (1990). Revision of the genera of gall crabs (Crustacea: Cryptochiridae) occurring in the Pacific Ocean. Pacific Science 44(4) 417-48. The family is currently placed in its own superfamily, Cryptochiroidea.
Gall crabs are sexually dimorphic, with males being much smaller than females. Contrary to females, most males are free-living and "visit" females for mating.van der Meij, S.E.T. (2014). Host species, range extensions, and an observation of the mating system of Atlantic shallow-water gall crabs (Decapoda: Cryptochiridae) Bulletin of Marine Science 90,1001-1010.
These crabs are most common in shallow waters where they live in association with stony corals, but they have also been recorded from mesophotic zones and deep waters.van der Meij, S.E.T., et al. (2015). A mesophotic record of the gall crab Opecarcinus hypostegus from a Curaçaoan reef. Bulletin of Marine Science 91, 205-206.van Tienderen, K.M. & S.E.T. van der Meij (2016). Occurrence patterns of coral-dwelling gall crabs (Cryptochiridae) over depth intervals in the Caribbean. PeerJ 4, e1794. They likely feed on mucus secreted by their coral hosts, as well as various detritus. Some species are thought to be filter feeders.
Because crab size is related to gall size, it is likely that the crabs form the galls, rather than living randomly in a dwelling within a coral. Related groups of gall crab taxa share a similar gall type, suggesting that the crabs influence the morphology of the galls.Wei, T. P., et al. (2013). Gall polymorphism of coral-inhabiting crabs (Decapoda, Cryptochiridae): a new perspective. Journal of Marine Science and Technology 21, 304-07.
The family contains the following twenty-one genera:
Cecidocarcinus Kropp & Manning, 1987 Cryptochirus Heller, 1861 Dacryomaia Kropp, 1990 Detocarcinus Kropp & Manning, 1987 Fizesereneia Takeda & Tamura, 1980 Fungicola Serene, 1966 †Galacticus Klompmaker, 2016 Hapalocarcinus Stimpson, 1859 Hiroia Takeda & Tamura, 1981 Kroppcarcinus Badaro, Neves, Castro & Johnsson, 2012 Lithoscaptus A. Milne-Edwards, 1862 Luciades Kropp & Manning, 1996 Neotroglocarcinus Fize & Serene, 1957 Opecarcinus Kropp & Manning, 1987 Pelycomaia Kropp, 1990 Pseudocryptochirus Hiro, 1938 Pseudohapalocarcinus Fize & Serène, 1956 Sphenomaia Kropp, 1990 Troglocarcinus Verrill, 1908 Utinomiella Kropp & Takeda, 1988 Xynomaia Kropp, 1990 Zibrovia Kropp & Manning, 1996
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