SYNOPTIC DESCRIPTION OF THE PHYLUM TUNICATA

EUKARYA>UNIKONTA>OPISTHOKONTA>ANIMALIA>BILATERIA>DEUTEROSTOMATA>TUNICATA

PHYLUM TUNICATA LINKS

The following description of the phylum Urochordata came from Margulis and Schwartz (1998), Buchsbaum (1938), Barnes (1980), Barnes (1984), Brusca and Brusca (2003), Hickman (1973), Nielsen (2001), Storer and Usinger (1965), Colbert and Morales (1991), Ruppert et al. (2004), and Tudge (2000).

I. SYNONYMS: Urochorda, Urochordata, tunicates, sea squirts.

II. NUMBER: 2150

III. PHYLUM CHARACTERISTICS:
- A. Structure
  - Symmetry: Bilateral.
  - Body Cavity: Eucoelomate but body cavity lost in adults.
  - Body Covering: Covered encased in external fibrous case or tunic, often of cellulose.
  - Support: Hydrostatic skeleton ( notochord (text with tooltip) in larval forms only).
  - Digestive System: Large pharynx with many gill slits (stigmata) for filter-feeding; food trapped in mucus; food tube short and simple, often U-shaped with anus near atrial siphon (text with tooltip) .
  - Circulatory System: Blood system with sinuses in mesenchyme; heart reverses periodically.
  - Locomotion: Usually adults are sessile (text with tooltip) .
  - Excretory System: Absent.
  - Nervous System: Simple in adults; ganglion (text with tooltip) between siphons from which nerves issue directly.
  - Endocrine System:
  - Respiratory System Absorption through pharynx.
- B. Reproduction:
  - Reproductive System: Hermaphroditic; often with one ovary and one testis. External fertilization. Asexual reproduction common.
  - Development: Embryo forms tadpole larva with muscular postanal tail, notochord and hollow dorsal nerve cord, usually tail reabsorbed when animal matures.
- C. Ecology: Sessile benthic (text with tooltip) or planktonic marine animals; filter-feeders, one group carnivorous.

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-Fernàndez, 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: 02/06/2013

SYNOPTIC DESCRIPTION OF THE PHYLUM TUNICATA

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