Cryptochiridae is a family of
crabs known commonly as gall crabs or coral gall crabs. They live inside dwellings in
coral
Corals are marine invertebrates within the class Anthozoa of the phylum Cnidaria. They typically form compact colonies of many identical individual polyps. Coral species include the important reef builders that inhabit tropical oceans and ...
s 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. The family is currently placed in its own
superfamily, Cryptochiroidea.
Gall crabs are
sexually dimorphic
Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most ani ...
, 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
Mucus ( ) is a slippery aqueous secretion produced by, and covering, mucous membranes. It is typically produced from cells found in mucous glands, although it may also originate from mixed glands, which contain both serous and mucous cells. It ...
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.
The family contains the following twenty-one genera:]
References
Crabs
Decapod families
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