- New Zealand pea crab
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New Zealand pea crab 
Scientific classification Kingdom: Animalia Phylum: Arthropoda Subphylum: Crustacea Class: Malacostraca Order: Decapoda Infraorder: Brachyura Family: Pinnotheridae Genus: Pinnotheres Species: P. novaezelandiae Binomial name Pinnotheres novaezelandiae
Filhol, 1886The New Zealand pea crab, Pinnotheres novaezelandiae, is a small, parasitic crab that lives most commonly inside New Zealand green-lipped mussels.[1] Adult females are about the size and shape of a pea, while adult males are smaller and flatter.[2] Adult New Zealand pea crabs are completely reliant on their host mussel for shelter and food, which it steals from the mussel's gills.[1] The New Zealand pea crab is found throughout New Zealand and can infect up to 70% of natural populations.[3] These crabs are of concern to green-lipped mussel aquaculture because they reduce the size and growth of mussels,[4] although infected mussels can be harvested and consumed.[5]
Contents
Description
Stage I adult male Pinnotheres novaezelandiae
Adult female New Zealand pea crabs have a soft-shelled exoskeleton.[2]Their carapace is oval in shape, ranging in size from 9.3 to 20.2 millimetres (0.37 to 0.80 in) wide.[3] Sexually mature adult females almost always have eggs that are tucked under their abdomens, giving them a more spherical appearance.[2] Adult females are opaque white in colour.[2] Developing eggs change colour from red to orange to yellow before they hatch, giving the brooding mother a different tint at each stage.[6] Adult male New Zealand pea crabs have a hard, chitinous exoskeleton.[3] Their carapace is smaller and more dorso-ventrally flattened than that of the female, ranging in size from 3.2 to 11.8 mm (0.13 to 0.46 in) wide.[3] Adult males are a creamy white colour with distinctive orange markings.[2]
Ecology
Female New Zealand pea crabs spend their entire adult lives within a single host.[7] Adult males will only leave their host in order to find a mate.[7] The hard exoskeleton and flattened body shape of the male New Zealand pea crab helps with this endeavour. New Zealand pea crabs are completely reliant on their host for food, shelter and a place to mate.[1] The New Zealand pea crab collects food by sitting on the gills of the green-lipped mussel and stealing food strands from the mussel.[4] The relationship between the New Zealand pea crab and the green-lipped mussel is one of parasitism because the crab damages the mussel's gills when taking food.[6] Infected mussels are also smaller and slower growing than uninfected mussels.[4]
The New Zealand pea crab is endemic to New Zealand and is common throughout the country, inhabiting the North Island, South Island, Stewart Island and the Chatham Islands.[6] The New Zealand pea crab lives most commonly in green-lipped mussels (Perna canaliculus), but can also be found in many other bivalve molluscs including the blue mussel (Mytilus edulis aoteanus), the Pacific oyster (Crassostrea gigas) and a species of clam (Chione stutchburyi).[8] The infection rate in wild green-lipped mussel populations can range from 0 to 70%.[3]
Edibility
Pea crabs are edible and were once a delicacy in the United States.[9][5] George Washington used to love having pea crabs floating in his oyster soup.[9] Mussels infected by pea crabs are also edible.[5]
References
- ^ a b c Stevens, P. M. (1990). "Specificity of host recognition of individuals from different host races of symbiotic pea crabs (Decapoda: Pinnotheridae)". Journal of Experimental Marine Biology and Ecology 143: 193–207. doi:10.1016/0022-0981(90)90070-S.
- ^ a b c d e Jones, J. B. (1977). "Post-planktonic stages of Pinnotheres novaezelandiae Filhol, 1886 (Brachyura: Pinnotheridae)". New Zealand Journal of Marine and Freshwater Research 11 (1): 145–158. doi:10.1080/00288330.1977.9515667.
- ^ a b c d e Jones, J. B. (1977). "Natural history of the pea crab in Wellington Harbour, New Zealand". New Zealand Journal of Marine and Freshwater Research 11 (4): 667–676. doi:10.1080/00288330.1977.9515704.
- ^ a b c Bierbaum, R. M.; Ferson, S. (1986). "Do symbiotic pea crabs decrease growth rate in mussels?". The Biological Bulletin 170 (1): 51–61. JSTOR 1541380.
- ^ a b c Maryland Seafood. "Seafood Information & Nutrition". http://www.marylandseafood.org/facts_and_nutrition/featured_species/oysters/qa.php. Retrieved 29 September 2011.
- ^ a b c Weir, R. G.; Feilder, D. R. (1985). The Marine Fauna of New Zealand: Larvae of the Brachyura (Crustacea, Decapoda). 92. 62–68. ISBN 9780477067225.
- ^ a b McLay, C. L. (1988). Brachyura and Crab-like Anomura of New Zealand. Leigh Marine Laboratory, New Zealand: University of Auckland Press. http://hdl.handle.net/2292/3450.
- ^ Palmer, P. (1995). "Occurence of a New Zealand pea crab, Pinnotheres novaezelandiae, in five species of surf clam". Marine and Freshwater Research 46 (7): 1071–1075. doi:10.1071/MF9951071.
- ^ a b Chefs. "Eating American Crabs". http://www.chefs.com/ArticleDetails.aspx?ArticleID=57. Retrieved 26 September 2011.
External links
Data related to Pinnotheres novaezelandiae at Wikispecies
Categories:- Pinnotheroidea
- Marine crustaceans of New Zealand
- Animals described in 1886
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