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| | EXTANT ANIMAL PHYLA (Site not responding. Last check: 2007-11-02) |
 | | Branch BILATERIA - Primary bilateral symmetry, secondarily modified to pentameral or radial, organ-system grade of organization, most triploblastic with well-developed mesoderm of endodermal origin, most with body cavity other than the digestive cavity, anus typically present. |
 | | Grade ACOELOMATA - No coelom, region between digestive tract and body wall filled with mesenchyme or mesoderm, if segmented youngest segments nearest head. |
 | | Grade PSEUDOCOELOMATA - Body cavity a pseudocoel (remnant of blastocoel, not lined with mesoderm on both sides), triploblastic. |
| people.uncw.edu /laws/GLY337/extant_animal_phyla.htm (431 words) |
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