Anomura
| Anomura Temporal range: Norian–Recent |
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| The hermit crab Dardanus megistos | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Subphylum: | Crustacea |
| Class: | Malacostraca |
| Order: | Decapoda |
| Suborder: | Pleocyemata |
| Infraorder: | Anomura Macleay, 1838 |
| Superfamilies | |
Anomura (sometimes Anomala) is a group of decapod crustaceans, including hermit crabs and others. Although the names of many anomurans includes the word crab, all true crabs are in the sister group to the Anomura, the Brachyura (the two groups together form the clade Meiura).[1]
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[edit] Description
The name Anomala reflects the unusual variety of forms in this group; whereas all crabs share some obvious similarities, the various groups of anomurans are quite dissimilar.[2] The name Anomura derives from an old classification in which reptant decapods were divided into Macrura (long-tailed), Brachyura (short-tailed) and Anomura (differently-tailed).
The group has been moulded by several instances of carcinisation – the development of a crab-like body form.[3] Thus, the king crabs (Lithodidae), porcelain crabs (Porcellanidae) and hairy stone crab (Lomisidae) are all separate instances of carcinisation.[3]
As decapods (meaning ten-legged), anomurans have ten pereiopods, but the last pair of these is often reduced in size, and hidden inside the gill chamber (under the carapace) to be used for cleaning the gills.[2] Since this arrangement is very rare in true crabs (for example, the small family Hexapodidae),[4] a "crab" with only eight visible pereiopods is generally an anomuran.[2]
There is wide acceptance from morphological and molecular data that Anomura and Brachyura (true crabs) are sister taxa, together making up the clade Meiura.[3]
[edit] Classification
The infraorder Anomura is divided into eight superfamilies:[5][6]
The oldest fossil attributed to Anomura is Platykotta, from the Norian–Rhaetian of the United Arab Emirates.[6]
Kiwa hirsuta was discovered in 2005 on a deep sea hydrothermal vent, and placed in a new family.[7] A second species, Kiwa puravida, was described in 2011.[8]
[edit] References
- ^ Gerhard Scholtz & Stefan Richter (1995). "Phylogenetic systematics of the reptantian Decapoda (Crustacea, Malacostraca)" (PDF). Zoological Journal of the Linnean Society 113 (3): 289–328. doi:10.1111/j.1096-3642.1995.tb00936.x. http://arthroinfo.org/pdfs/826/826.pdf.
- ^ a b c Gary Poore (2004). "Anomura – hermit crabs, porcelain crabs and squat lobsters". Marine Decapod Crustacea of Southern Australia: a Guide to Identification. CSIRO Publishing. pp. 215–287. ISBN 9780643099258. http://books.google.co.uk/books?id=TptuZCY3OU0C&pg=PA215.
- ^ a b c Shane T. Ahyong, Kareen E. Schnabel & Elizabeth W. Maas (2009). "Anomuran phylogeny: new insights from molecular data". In Joel W. Martin, Keith A. Crandall & Darryl L. Felder. Decapod Crustacean Phylogenetics. Crustacean issues. 18. CRC Press. pp. 399–414. doi:10.1201/9781420092592-c20. ISBN 978-1-4200-9258-5. http://books.google.co.uk/books?id=Bxs6SgSW2kQC&pg=PA399.
- ^ Carrie E. Schweitzer & Rodney M. Feldmann (2001). "Differentiation of the fossil Hexapodidae Miers, 1886 (Decapoda: Brachyura) from similar forms". Journal of Paleontology 75 (2): 330–345. doi:10.1666/0022-3360(2001)075<0330:DOTFHM>2.0.CO;2. http://decapoda.nhm.org/pdfs/10789/10789.pdf.
- ^ Sammy De Grave, N. Dean Pentcheff, Shane T. Ahyong et al. (2009). "A classification of living and fossil genera of decapod crustaceans". Raffles Bulletin of Zoology Suppl. 21: 1–109. http://rmbr.nus.edu.sg/rbz/biblio/s21/s21rbz1-109.pdf.
- ^ a b Jérôme Chablais, Rodney M. Feldmann & Carrie E. Schweitzer (2011). "A new Triassic decapod, Platykotta akaina, from the Arabian shelf of the northern United Arab Emirates: earliest occurrence of the Anomura" (PDF). Paläontologische Zeitschrift 85: 93–102. doi:10.1007/s12542-010-0080-y. http://decapoda.nhm.org/pdfs/31744/31744.pdf.
- ^ Enrique Macpherson, William Jones & Michel Segonzac (2005). "A new squat lobster family of Galatheoidea (Crustacea, Decapoda, Anomura) from the hydrothermal vents of the Pacific-Antarctic Ridge" (PDF). Zoosystema 27 (4): 709–723. http://www.mnhn.fr/museum/front/medias/publication/6892_z05n4a3.pdf.
- ^ Andrew R. Thurber, William J. Jones & Kareen Schnabel (2011). "Dancing for food in the deep sea: bacterial farming by a new species of yeti crab". PLoS ONE 6 (11): e26243. doi:10.1371/journal.pone.0026243. http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0026243.
[edit] External links
Media related to Anomura at Wikimedia Commons
Data related to Anomura at Wikispecies
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