Sometimes referred to as Coelenterata, phylum Cnidaria consists of aquatic, invertebrate animals. Characteristic of animals within this phylum are radial symmetry, a gastrovascular cavity, and cnidae (capsule-like organelles capable of everting). Cnidaria may be broken up into four classes:
Anthozoa coral Sea pen Anemone
Scyphozoa Cubozoa back
For the billionth time… Radial symmetry... IN ACTION! back
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Macer, Darryl. “Bioethics Dictionary.” Eubios Ethics Institute. 2008. Eubios Ethics Institute. 4 February 2008 < http:// www.eubios.info/biodict.htm >.
“ Sea Pen.” Wikipedia. 2007. Wikimedia Foundation, Inc. 4 February 2008 <http://en.wikipedia.org/wiki/Sea_pen>.