Parazoa
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| Parazoa Fossil range: Ediacaran - Recent |
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 A sponge
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The Parazoa are an ancestral subkingdom of animals, literally translated as "beside the animals". Parazoans differ from their choanoflagellate ancestors in that they are macroscopic and have differentiated cells, but unlike "true animals" (Eumetazoa), they do not have tissues. The only surviving parazoans are the sponges, which belong to the phylum Porifera. Some include Placozoa, a phylum that consists of only one species, Trichoplax adhaerens, in the division, but they are also sometimes placed in the subkingdom Agnotozoa. Parazoa are asymmetrical (meaning they display no symmetry) all other animals will display some sort of symmetry. There are currently 5000 species, 150 of which are freshwater. Larvae are planktonic and adults are sessile.
[edit] References
- http://www.jochemnet.de/fiu/BSC1011/BSC1011_12/sld001.htm
- Biology 7th edition, Campbell and Reece, 2005
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