Oikopleura is a genus of tunicates in the class Appendicularia (larvaceans). An organism of this genus 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 filters very actively, 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. About half of Oikopleura species are bioluminescent.
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 oikopleurid genera, namely: Folia, Stegosoma, Mesoikopleura, and Megalocercus. The genus might also harbour more diversity than thought, with species complexes like Oikopleura dioica comprising several reproductively incompatible clades despite consistent general morphology.
List of species
Oikopleura (Coecaria) , 1933 Oikopleura (Coecaria) fusiformis Fol, 1872 Oikopleura (Coecaria) fusiformis cornutogastra Aida, 1907 Oikopleura (Coecaria) gracilis Lohmann, 1896 Oikopleura (Coecaria) intermedia Lohmann, 1896 Oikopleura (Coecaria) longicauda (Vogt, 1854) Oikopleura (Vexillaria) Lohmann, 1933 Oikopleura (Vexillaria) albicans (Leuckart, 1853) Oikopleura (Vexillaria) caudaornata (Fenaux & Youngbluth, 1991) Oikopleura (Vexillaria) cophocerca (Gegenbaur, 1855) Oikopleura (Vexillaria) dioica Fol, 1872 Oikopleura (Vexillaria) gaussica Lohmann, 1905 Oikopleura (Vexillaria) gorskyi Flood, 2000 Oikopleura (Vexillaria) inflata (Fenaux & Youngbluth, 1991) Oikopleura (Vexillaria) labradoriensis Lohmann, 1892 Oikopleura (Vexillaria) parva Lohmann, 1896 Oikopleura (Vexillaria) rufescens Fol, 1872 Oikopleura (Vexillaria) vanhoeffeni Lohman, 1896 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 hox genes are distributed in nine locations around the genome whereas other chordates have a cluster of hox genes. Of note, this is the first chordate among the eukaryotes found to have operons.
References
External links
Integrated Taxonomic Information System (ITIS): Oikopleura Taxonomic Serial No.: 159668 National Center for Biotechnologu Information (NCFI): Oikopleura Taxonomy ID: 34763 Jellieszone: Oikopleura dioica Fol, 1872 : Larvacean Oikopleura Genome Browser Merriam-Webster: Oikopleura
Videos Youtube: Larvacea (Oikopleura dioica)
Photos Flickr: Oikopleura sp. in the house