HIERARCHICAL CLASSIFICATION OF THE PHYLUM TUNICATA
| EUKARYA>UNIKONTA>OPISTHOKONTA>ANIMALIA>BILATERIA>DEUTEROSTOMATA>TUNICATA |
PHYLUM TUNICATA LINKS
| This taxonomy is taken from the system of Brusca and Brusca (2003). However, the elevation of the the tunicates from a subphylum of Chordata to its own phylum is from Nielsen (2001). The phylum as presented here has four classes, but Tsagkogeorga et al. (2009) suggest that the Ascideacea is polyphyletic |
- CLASS ASCIDIACEA (4 ORDERS)
- Sessile;
branchial
(text with tooltip)
The branchial siphon is the incurrent siphon.
and atrial siphons close together; life-cycle simple, without alternation of sexual and asexual generations.
- Ascidia, Botryllus, Chelyosoma, Ciona, Clavelina, Corella, Diazona, Diplosoma, Halocynthia, Lissoclinum, Molgula, Polycarpa, Psammascidia, Pyura, Styela.
- Sessile;
branchial
(text with tooltip)
The branchial siphon is the incurrent siphon.
and atrial siphons close together; life-cycle simple, without alternation of sexual and asexual generations.
- CLASS THALIACEA (3 ORDERS)
- Planktonic; branchial and atrial siphons at opposite ends of barrel-shaped or fusiform body; exhalant water current provides propulsive force for movement; either colonial or alternate between solitary and colonial forms; asexual buds formed on ventral stolon.
- Dolioletta, Doliolum, Pyrosoma, Salpa, Thetys.
- Planktonic; branchial and atrial siphons at opposite ends of barrel-shaped or fusiform body; exhalant water current provides propulsive force for movement; either colonial or alternate between solitary and colonial forms; asexual buds formed on ventral stolon.
- CLASS APPENDICULARIA (ALSO CALLED LARVACEA, 1 ORDER)
- Small, solitary;
neotenous
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Neoteny is the situation in which an immature form becomes sexually mature in the developmental history.
; with large tail; secrete gelatinous house through filters of which water is drawn by beating movements of the tail; when the house is clogged, it is discarded and a new one is secreted; pharynx with 2 stigmata opening directly to body surface; endostyle reduced; tail with notochord and nerve cord, much larger than body.
- Fritillaria, Oikopleura, Stegasoma.
- Small, solitary;
neotenous
(text with tooltip)
Neoteny is the situation in which an immature form becomes sexually mature in the developmental history.
; with large tail; secrete gelatinous house through filters of which water is drawn by beating movements of the tail; when the house is clogged, it is discarded and a new one is secreted; pharynx with 2 stigmata opening directly to body surface; endostyle reduced; tail with notochord and nerve cord, much larger than body.
- CLASS SORBERACEA (1 ORDER)
- Ascidian-like, but carnivorous, no perforated branchial sac. They keep a dorsal nerve cord as adults. Abyssal.
- Gasterascidia, Hexadactylus, Oligotrema, Sorbera, Octacnemus.
- Ascidian-like, but carnivorous, no perforated branchial sac. They keep a dorsal nerve cord as adults. Abyssal.
| LITERATURE CITED Barnes, R. D. 1980. Invertebrate Zoology. Saunders College/Holt, Rinehart and Wilson, Philadelphia. Barnes. R. S. K. 1984a. Kingdom Animalia. IN: R. S. K. Barnes, ed. A Synoptic Classification of Living Organisms. Sinauer Associates, Inc., Sunderland, MA. pp. 129-257. Bourlat, S. J., T. Juliusdottir, C. J. Lowe, R. Freeman, J. Aronowicz, M. Kirschner, E. S. Lander, M. Thorndyke, H. Nakano, A. B. Kohn, A. Heyland, L. L. Moroz, R. R. Copley, and M. J. Telford. 2006. Deuterostome phylogeny reveals chordates and the new phylum Xenoturbellida. Nature. 444: 85-88. Brusca, R. C. and G. J. Brusca. 2003. Invertebrates. Sinauer Associates, Inc. Sunderland, Mass. Buchsbaum, R. 1938. Animals Without Backbones, An Introduction to the Invertebrates. The University of Chicago Press. Chicago. Cameron, C. B., J. R. Garey, and B. J. Swalla. 2000. Evolution of the Chordata body plan: New insights from phylogenetic analyses of deuterostome phyla. Proceedings of the National Academy of Sciences. U.S.A. 97: 4469-4474. Colbert, E. H. and M. Morales. 1991. Evolution of the Vertebrates, A History of the Backboned Animals Through Time. WILEY-LISS, Inc. New York. Delsuc, F., H. Brinkmann, and H. Philippe. 2005. Phylogenomics and the reconstruction of the tree of life. Nature Reviews: Genetics. 6:361-375. Halanych, K.M. 1995. The phylogenetic position of the pterobranch hemichordates based on 18S rDNA sequence data. Molecular Phylogenetics and Evolution. 4(1): 72-76. Hickman, C. P. 1973. Biology of the Invertebrates. The C. V. Mosby Company. Saint Louis. Jeffery, W. R., A. G. Strickler, and Y. Yamamoto. 2004. Migratory neural crest-like cells form body pigmentation in a urochordate embryo. Nature. 431: 696-699. Margulis, L. and K. Schwartz. 1998. Five kingdoms, an illustrated guide to the phyla of life on earth. 3rd Edition. W. H. Freeman and Company. New York. [C] Nielsen, C. 2001. Animal Evolution: Interrelationships of the Living Phyla. 2nd Edition. Oxford University Press. Oxford. Pechenik, J. A. 2005. Biology of the Invertebrates. McGraw-Hill. New York. Putnam, N. H., T. Butts, D. E. K. Ferrier, R. F. Furlong, U. Hellsten, T. Kawashima, M. Robinson-Rechavi, E. Shoguchi, A. Terry, J.-K. Yu, E. Benito-Gutiérrez, I. Dubchak, J. Garcia-Fernà ndez, J. J. Gibson-Brown, I. V. Grigoriev, A. C. Horton, P. J. de Jong, J. Jurka, V. V. Kapitonov, Y. Kohara, Y. Kuroki, E. Lindquist, S. Lucas, K. Osoegawa, L. A. Pennacchio, A. A. Salamov, Y. Satou, T. Sauka-Spengler, J. Schmutz, T. Shin-I, A. Toyoda, M. Bronner-Fraser, A. Fujiyama, L. Z. Holland, P. W. H. Holland, N. Satoh, and D. S. Rokhsar. 2008. The amphioxus genome and the evolution of the chordate karyotype. Nature. 453: 1064-1071. Ruppert, E. E., R. S. Fox, and R. D. Barnes. 2004. Invertebrate Zoology: A Functional Evolutionary Approach. Seventh Edition. Thomson, Brooks/Cole. New York. pp. 1-963. Storer, T. I. and R. L. Usinger. 1965. General Zoology. 4th Edition. McGraw-Hill Book Company. New York. Swalla, B. J. and A. . Smith. 2008. Deciphering deuterostome phylogeny: molecular, morphological and palaeontological perspectives. Phil. Trans. R. Soc. B. 363:1557-1568. Tudge, C. 2000. The Variety of Life, A Survey and a Celebration of all the Creatures That Have Ever Lived. Oxford University Press. New York. |
| By Jack R. Holt and Carlos A. Iudica. Last revised: 01/25/2013 |
