Oikopleura is a genus of in the class Larvacean (larvaceans). It forms a mucus house every four hours at 20 degrees Celsius. This house has a coarse mesh to keep out big particles, and a fine mesh that collects the small particles, down to the nanoplankton that includes (pelagic) bacteria.
Abandoned mucus houses sink to the deep, collecting organic particles during their descent. They make an important contribution to marine snow, since Oikopleura is abundant and is a very active filtered, using powerful strokes of its tail. Its abundance is less obvious from preserved samples (that are usually analyzed) because the gelatinous body disappears in the preservation process while leaving hardly any trace.
Species of Oikopleura have the smallest genomes in the animal kingdom, only about 75Mb.
Oikopleura contains bioluminescent species.
Etymology
The genus name comes from
oikos (meaning "house") and
pleura ("rib", or "side of the body"), referring to their ability to build a mucus house like other larvaceans.
Taxonomy
Phylogeny
Oikopleura has been found to possibly be paraphyletic with respect to several other
Oikopleuridae genera, namely:
Folia,
Stegosoma,
Mesoikopleura, and
Megalocercus. The genus might also harbour more diversity than thought, with
like
Oikopleura dioica comprising several reproductively incompatible clades despite consistent general morphology.
List of species
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Oikopleura (Coecaria) , 1933
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Oikopleura (Coecaria) fusiformis Fol, 1872
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Oikopleura (Coecaria) fusiformis cornutogastra Aida, 1907
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Oikopleura (Coecaria) gracilis Lohmann, 1896
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Oikopleura (Coecaria) intermedia Lohmann, 1896
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Oikopleura (Coecaria) longicauda (Vogt, 1854)
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Oikopleura (Vexillaria) Lohmann, 1933
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Oikopleura (Vexillaria) albicans (Leuckart, 1853)
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Oikopleura (Vexillaria) caudaornata (Fenaux & Youngbluth, 1991)
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Oikopleura (Vexillaria) cophocerca (Gegenbaur, 1855)
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Oikopleura (Vexillaria) dioica Fol, 1872
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Oikopleura (Vexillaria) gaussica Lohmann, 1905
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Oikopleura (Vexillaria) gorskyi Flood, 2000
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Oikopleura (Vexillaria) inflata (Fenaux & Youngbluth, 1991)
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Oikopleura (Vexillaria) labradoriensis Lohmann, 1892
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Oikopleura (Vexillaria) parva Lohmann, 1896
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Oikopleura (Vexillaria) rufescens Fol, 1872
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Oikopleura (Vexillaria) vanhoeffeni Lohman, 1896
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Oikopleura (Vexillaria) villafrancae Fenaux, 1992
Distribution
The oikopleurids are distributed in the tropical waters of all oceans and seas of the globe, having been reported widely in the
Caribbean Sea and the western coasts of the
Atlantic Ocean.
[Flores-Coto C. 1965: Notas preliminares sobre la identificación de las apendicularias de las aguas veracruzanas. Anales del Instituto de Biología (México) 35: 293-296.][Flores-Coto C.. 1974: Contribución al conocimiento de las apendicularias del arrecife “La Blanquilla” Veracruz, México con descripción de una nueva especie. Anales del Centro de Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México 1: 41-60.][Flores-Coto, César., Sanvicente-Añorve, Laura. & Sánchez-Ramírez, Marina. 2010: Appendicularian distribution and diversity in the southern Gulf of Mexico. Distribución y diversidad de apendicularias en el sur del golfo de México. Revista Mexicana de Biodiversidad, 81:123- 131. PDF ][Castellanos, I. A. and E. Suárez-Morales. 2009. Appendicularia (Urochordata) of the Gulf of Mexico, Pp. 1217–1221 in Felder, D.L. and D.K. Camp (eds.), Gulf of Mexico–Origins, Waters, and Biota. Biodiversity. Texas A&M Press, College Station, Texas.][Márquez, Brightdoom., Marín, Baumar., Zoppi, Evelyn. & Moreno, Carlos. 2006: Zooplancton del Golfo De Cariaco. Bol. Inst. Oceanogr. Venezuela, Univ. Oriente. 45(1):61-78 PDF ][Zoopp, Evelyn. 1971: Apendicularias de la Región Oriental de Venezuela. Studies on the Fauna of Curaçao and other caribbean Island, 132:76-109. Lam I – VI.][Esnal G. 1972: Apendicularias de la desembocadura del Río de la Plata. Physis (Argentina) 31: 259-272.][Esnal G. 1973: Apendicularias de las costas argentinas. Physis (Argentina) 32: 267-273.][Esnal G. 1979: Características generales de la distribución de tunicados pelágicos del Atlántico sudoccidental, con algunas observaciones morfológicas. Physis (Argentina) 38: 91-102.][Esnal G. 1981: Apendicularia. In: Boltovskoy (ed) Atlas del zooplancton del Atlántico sudoccidental y métodos de trabajo con el zooplancton marino: 809-820. Publicación Especial, Instituto Nacional de Investigación y Desarrollo Pesquero, Mar del Plata, Argentina. 936 pp.][Esnal G. 1999: Appendicularia. In: Boltovskoy D (ed). South Atlantic zooplancton: 1375-1399. Backhuys Publication, Leiden, The Netherlands.]
Oikopleura dioica
A species of particular interest under this genus is the
Oikopleura dioica, which is an anomaly among
chordates. It has retained the fundamental body plan of the chordate; yet, it has lost the mechanism for
retinoic acid signaling which operates during chordate development. The loss raises the question of the evolutionary constraints that have prevented similar changes in the other chordates.
Oikopleura dioica are distributed in nine locations around the genome whereas other have a cluster of hox genes.
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