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Image from Wikipedia.
Phylum Cnidaria (hydroids, jellyfish, anemones, corals, etc.)

Fewer than 1% of cnidarian species occur in freshwater. The phylum is perhaps best known for marine jellyfish, corals, and sea anemone. In freshwater, the Cnidaria is represented by the Class Hydrozoa. However, only a few dozen species are known from inland habitats, and probably only about 10 occur in North America (Jankowski et al. 2008).

The cnidarians represent a zoological advance in complexity over the Porifera in that they go through the developmental process of gastrulation and possess true tissues -- like other groups of metazoans. However, members of the Cnidaria only have two embryonic tissue layers. A unique characteristic of this phylum is alternation of generation between an asexual polyp stage and a sexual medusa stage (although one or the other may be suppressed in various taxa). The body plan is radially symmetrical with only a diffuse nerve net rather than a central nervous system.

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Bibliography

  • Zhang, Z.-Q. 2011. Animal biodiversity: An introduction to higher-level classification and taxonomic richness. Zootaxa 3148: 7-12. [Available online]
  • Slobodkin, L.B. & P.E. Bossert. 2010. Cnidaria. [in] J.H. Thorp & A.P. Covich (eds.). Ecology and Classification of North American Freshwater Invertebrates, 3rd edition: 125-142.
  • Jankowski, T., A.G. Collins & R. Campbell. 2008. Global diversity of inland water cnidarians. Hydrobiologia 595: 35-40. [Available online]
  • Daly, M., M.R. Brugler, P. Cartwright, A.G. Collins, M.N. Dawson, D.G. Fautin, S.C. France, C.S. McFadden, D.M. Opresko, E. Rodriguez, S.L. Romano & J.L. Stake. 2007. The phylum Cnidaria: A review of phylogenetic patterns and diversity 300 years after Linnaeus. Zootaxa 1668: 127-182. [Available online]
  • Brusca, R.C. & G.J. Brusca. 2003. Invertebrates, 2nd edition. Sinauer Associates, Inc., Sunderland, Massachusetts. 936 pp.
  • Smith, D.G. 2001. Cnidaria (Hydroids, jellyfish). Pennak's Freshwater Invertebrates of the United States, 4th edition: 61-76.
  • Jankowski, T. 2001. The freshwater medusae of the world — a taxonomic and systematic literature study with some remarks on other inland water jellyfish. Hydrobiologia 462: 91-113. [Available online]
  • Dumont, H.J. 1994. The distribution and ecology of the fresh- and brackish-water medusae of the world. Hydrobiologia 272: 1-12.
  • Underhill, J.C., W.D. Schmid & D.E. Gilbertson. 1982. Taxonomic Keys to the Common Animals of the North Central States, exclusive of the parasitic worms, terrestrial insects, and birds, 4th edition. 205 pp.
  • Hyman, L.H. 1959. Coelenterata. [in] W.T. Edmondson (ed.). Ward & Whipple Fresh-Water Biology, 2nd edition: 313-322.

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Classification of Freshwater Taxa

Only taxa found in North America are listed. Formatting indicates if they are known (to us) from North America, the midwestern states or Wisconsin.

Kingdom Animalia [details]
Subkingdom Eumetazoa [details]
Superphylum Radiata [details]
Phylum Cnidaria (hydroids, jellyfish, anemones, corals, etc.) [details]
  .   Subphylum Medusozoa [details]
  .    .   Class Hydrozoa (hydroids) [details]
  .    .    .   Subclass Trachylinae [details]
  .    .    .    .   Order Limnomedusae (+ Limnohydrina) [details]
  .    .    .    .    .   Family Olindiidae (+ Olindiadidae, + Olindiasidae) [details]
  .    .    .    .    .    .   Genus Craspedacusta [details]
  .    .    .    .    .    .    .   Species C. sowerbyi (+ C. sowerbii) (freshwater jellyfish) [detail]
  .    .    .    .    .    .   Genus Calpasoma [details]
  .    .    .    .    .    .    .   Species C. dactylopterum [detail]
  .    .    .   Subclass Hydroidolina (+ Hydroidomedusae) [details]
  .    .    .    .   Order Anthoathecata (+ Athecata, + Anthomedusae) [details]
  .    .    .    .    .   Suborder Aplanulata [details]
  .    .    .    .    .    .   Family Hydridae (hydras) [details]
  .    .    .    .    .    .    .   Genus Hydra (+ Chlorohydra) [details]
  .    .    .    .    .    .    .    .   Species H. canadensis (+ H. pseudoligactis), H. oligactis (+ H. fusca), H. viridissima (+ H. viridis), H. vulgaris (+ H. americana, + H. littoralis, + H. carnea), H. cauliculata, ..., etc.
  .    .    .    .    .    .   Family Protohydridae [details]
  .    .    .    .    .    .    .   Genus Protohydra [details]
  .    .    .    .    .    .    .    .   Species P. leuckarti [detail]
  .    .    .    .    .   Suborder Filifera [details]
  .    .    .    .    .    .   Family Cordylophoridae [details]
  .    .    .    .    .    .    .   Genus Cordylophora [details]
  .    .    .    .    .    .    .    .   Species C. caspia (+ C. lacustris) [detail]
  .    .   Class Polypodiozoa [details]
  .    .    .   Family Polypodiidae [details]
  .    .    .    .   Genus Polypodium [details]
  .    .    .    .    .   Species P. hydriforme [detail]

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