HIERARCHICAL CLASSIFICATION OF THE PHYLUM HEMICHORDATA
| EUKARYA>UNIKONTA>OPISTHOKONTA>ANIMALIA>BILATERIA>DEUTEROSTOMATA>HEMICHORDATA |
PHYLUM HEMICHORDATA LINKS
| This is the taxonomic system of Brusca and Brusca (2003). The Class Planktosphaerida is problematic in that it likely is just a tornaria larva of an eneropneust. |
- CLASS ENTEROPNEUSTA (1 ORDER)
- Solitary; freely mobile, vermiform, up to 2.5M long; without tentacular arms on collar; reduced coelomic cavities; straight gut with terminal anus; many pharyngial gill slits, new slits produced throughout life; long proboscis, short collar, very long trunk; with marked powers of regeneration and asexual reproduction; larval stage a
tornaria
(text with tooltip)
A tornaria larva is a characteristic larval form of hemichordates. It is planktonic, transparent, and long-lived.
; inhabit U-shaped mucus-lined burrows. Proboscis cilia collect food.
- Balanoglossus, Protoglossus, Saccoglossus, Saxipendium, Spengella, Xenopleura.
- Solitary; freely mobile, vermiform, up to 2.5M long; without tentacular arms on collar; reduced coelomic cavities; straight gut with terminal anus; many pharyngial gill slits, new slits produced throughout life; long proboscis, short collar, very long trunk; with marked powers of regeneration and asexual reproduction; larval stage a
tornaria
(text with tooltip)
A tornaria larva is a characteristic larval form of hemichordates. It is planktonic, transparent, and long-lived.
; inhabit U-shaped mucus-lined burrows. Proboscis cilia collect food.
- CLASS PTEROBRANCHIA (2 ORDERS)
- Colonial, sessile, inhabiting tubes secreted by shield-shaped proboscis; body sac-like, with stalk and arms on collar; U-shaped gut, anus on collar; at most 1 pair of pharyngial gill slits; without neurochord, mid-dorsal collar only with thickened epidermal plexus; glomerulus poorly developed; asexual reproduction common.
- Atubaria, Cephalodiscus, Rhabdopleura,
- Colonial, sessile, inhabiting tubes secreted by shield-shaped proboscis; body sac-like, with stalk and arms on collar; U-shaped gut, anus on collar; at most 1 pair of pharyngial gill slits; without neurochord, mid-dorsal collar only with thickened epidermal plexus; glomerulus poorly developed; asexual reproduction common.
- CLASS PLANKTOSPHAERIDA (1 ORDER)
- A “class” created for a giant tornaria larva (up to 25mm in diameter); the spherical body has coelomic cavities; a very sinuous band of cilia; and a differentiated gut. Assumed to be the larval stage of an unknown hemichordate.
- Planktosphaera.
- A “class” created for a giant tornaria larva (up to 25mm in diameter); the spherical body has coelomic cavities; a very sinuous band of cilia; and a differentiated gut. Assumed to be the larval stage of an unknown hemichordate.
| 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. 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: 01/25/2010 |
