- Porcelain crab
Taxobox
name = Porcelain crabs
image_width = 280px
image_caption = Porcelain anemone crab, "Neopetrolisthes sp." with thesea anemone "Condylactis sp."
regnum =Animal ia
phylum =Arthropod a
classis =Malacostraca
ordo =Decapoda
subordo =Pleocyemata
infraordo =Anomura
superfamilia =Galatheoidea
familia = Porcellanidae
familia_authority = Haworth, 1825
subdivision_ranks = Genera
subdivision = See text.Porcelain crabs are decapod
crustacea ns in the family Porcellanidae, which superficially resemble truecrab s. They are a good example ofcarcinisation , whereby a non-crab-like animal (in this case a relative of asquat lobster ) evolves into an animal that only a specialist would know is not a true crab. They live in all the world's oceans, except theArctic Ocean and theAntarctic .Porcelain crabs are small, usually with body widths of 1-2 cm.They are common under rocks, and can often be found and observed on rocky
beach es and shorelines, startled creatures scurrying away when a stone is lifted.Porcelain crabs can be distinguished from the true crabs by the apparent number of walking legs (three instead of four pairs, the fourth pair is actually hidden under the
carapace ), the apparent lack of a wrist (carpal) segment on thecheliped s, and long antennae originating on the front outside of the eye stalks. Theabdomen of the porcelain crab is long and folded underneath it, free to move. In fact, when alarmed, the crab might swim by flapping its abdomen.Porcelain crabs share the general body plan of a
squat lobster (Galatheidae), but their bodies are more compact and flattened, an adaptation for living and hiding under rocks, as well as squeezing into little nooks and crannies. The porcelain crabs are quite fragile animals, and will often shed their limbs, hence their name. This trait is useful for these crustaceans because it helps them escape if a limb is grabbed by a predator or caught between rocks shifting in the current. A broken-off piece of limb may still continue to move for a short while, distracting the would-be predator as the crustacean flees. The lostappendage can grow back over several moultings. Porcelain crabs have large "chelae" (claw s), which are used for territorial struggles, but not for catching food. Feeding is accomplished instead by combingplankton and other organic particles from the water using longseta e (feathery hair or bristle-like structures) on the mouthparts, where they will later be scraped off and consumed into the mouth. These animals will also scavenge on the sea floor fordetritus and in aquaria, they will consume meaty pieces offish orshrimp .Some of the common species of porcellanids in the Caribbean are "Petrolisthes quadratus", found in large numbers under rocks in the intertidal, and the red-and-white polka-dotted "Porcellana sayana", which lives commensally within the shells inhabited by large
hermit crab s.Genera
* "
Aliaporcellana " Nakasone & Miyake, 1969
* "Capilliporcellana " Haig, 1981
* "Clastotoechus " Haig, 1960
* "Euceramus " Stimpson, 1858
* "Enosteoides " Johnson, 1970
* "Eulenaios " Ng & Nakasone, 1993
* "Lissoporcellana " Haig, 1978
* "Megalobrachuium " Stimpson, 1858
* "Minyocerus " Stimpson, 1858
* "Neopetrolisthes " Miyake, 1937
* "Neopisoma " Haig, 1960
* "Pachycheles " Ward, 1942
* "Parapetrolisthes " Haig, 1962
* "Petrolisthes " Stimpson, 1858
* "Pisidia" Leach, 1820
* "Polyonyx " Stimpson, 1858
* "Porcellana " Lamarck, 1801
* "Porcellanella " White, 1852
* "Pseudoporcellanella " Sankarankutty, 1961
* "Raphidopus " Stimpson, 1858
* "Ulloaia " Glassell, 1938References
* [http://crustacea.net/crustace/anomura/www/porcella.htm Porcelain crab info] from crustacea.net
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