Web document 18.2. The Phylum Bilateria.
The bilateria are bilaterally symmetric animals. The coelom is the body cavity of an animal. Acoelomata lack a body cavity. Coelomata have a body cavity that is lined with mesodermal tissue, while Pseudocoelomata such as the nematode C. elegans have a body cavity lined with other tissue.
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TABLE 18-9 Phylum Bilateria |
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Superphylum |
Phylum |
Species Example |
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Acoelomata |
Platyhelminthes (flatworms) |
Schistosoma mansoni |
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Coelomata |
Deuterostomia (e.g. chordates, echinoderms, arrow worms) |
Homo sapiens |
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Protostomia [e.g. mollusks, leeches, arthropods (insects)] |
Drosophila melanogaster |
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Pseudocoelomata |
Acanthocephala (thorny-headed worms) |
Moniliformis moniliformis |
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Cycliophora |
Symbion pandora |
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Gastrotricha |
Draculiciteria tesselata |
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Kinorhyncha |
Pycnophyes kielensis |
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Nematoda (roundworms) |
Caenorhabditis elegans |
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Nematomorpha (horsehair worms) |
Gordius aquaticus |
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Rotifera |
Adineta vaga |
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Source: Adapted from the classification at NCBI (► http://www.ncbi.nlm.nih.gov/Taxonomy/). |
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