Maxillopoda

Maxillopoda Temporal range: Mid Cambrian–Recent PreЄ Є O S D C P T J K Pg N
Cyclops (Copepoda: Cyclopoida)
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Subphylum:	Crustacea
Class:	Maxillopoda Dahl, 1956 [1]
Sub-classes
Thecostraca Tantulocarida Branchiura Pentastomida Mystacocarida Copepoda

Maxillopoda is a diverse class of crustaceans including barnacles, copepods and a number of related animals. It does not appear to be a monophyletic group, and no single character unites all the members.^[2]

Description

With the exception of some barnacles, maxillopodans are mostly small,^[3] including the smallest known arthropod, Stygotantulus stocki.^[2]. They often have short bodies, with the abdomen reduced in size, and generally lacking any appendages ^[3] This may have arisen through paedomorphosis.^[3]

Apart from barnacles, which use their legs for filter feeding, most maxillopodans feed with their maxillae. They have a bauplan comprising 5 cephalic segments, 6 thoracic segments and 4 abdominal segments, followed by a telson.^[4]

Fossil record

The fossil record of the group extends back into the Cambrian, with fossils of both barnacles^[5] and tongue worms^[6] known from that period.

Classification

Six subclasses are generally recognised, although many works have further included the ostracods among the Maxillopoda.^[2] Of the six groups, only Mystacocarida are entirely free-living; all the members of the Tantulocarida, Pentastomida and Branchiura are parasitic, and many of the Copepoda and Thecostraca are parasites.

Subclass	Members	Photo
Copepoda	Calanoida Cyclopoida Gelyelloida Harpacticoida Misophrioida Monstrilloida Mormonilloida Platycopioida Poecilostomatoida Siphonostomatoida	Calocalanus pavo (Calanoida: Calocalanidae)
Thecostraca	Cirripedia (barnacles) Facetotecta Ascothoracida	Chthamalus stellatus (Sessilia: Chthamalidae)
Branchiura	Arguloida (fish lice) † Cyclida	Argulus on a stickleback (Argulidae)
Pentastomida (tongue worms)	Cephalobaenida Porocephalida	Armillifer armillatus (Porocephalidae)
Mystacocarida	Ctenocheilocaris Derocheilocaris	Ctenocheilocaris (Derocheilocarididae)
Tantulocarida	Basipodellidae Deoterthridae Doryphallophoridae Microdajidae

References

Crustaceans portal

1. ^ "Maxillopoda". Integrated Taxonomic Information System. http://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=621145. Retrieved October 7, 2010. 
2. ^ ^{a b c} Joel W. Martin & George E. Davis (2001) (PDF). An Updated Classification of the Recent Crustacea. Natural History Museum of Los Angeles County. pp. 132. http://atiniui.nhm.org/pdfs/3839/3839.pdf. 
3. ^ ^{a b c} "Introduction to Maxillopoda". University of California, Berkeley. http://www.ucmp.berkeley.edu/arthropoda/crustacea/maxillopoda.html. Retrieved December 31, 2009. 
4. ^ Phil Myers (2001). ""Maxillopoda"". Animal Diversity Web. http://animaldiversity.ummz.umich.edu/site/accounts/information/Maxillopoda.html. Retrieved December 31, 2009. 
5. ^ B. A. Foster & J. S. Buckeridge (1987). "Barnacle palaeontology". In A. J. Southward. Crustacean Issues 5: Barnacle Biology. pp. 41–63. ISBN 90-6191-628-3. 
6. ^ Dieter Waloszek, John E. Repetski & Andreas Maas (2005). "A new Late Cambrian pentastomid and a review of the relationships of this parasitic group". Transactions of the Royal Society of Edinburgh: Earth Sciences 96: 163–176. doi:10.1017/S0263593300001280.