| Mesozoa |
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| This
phylum's 'place' relative to other phyla:
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Selected
taxa within this taxon:
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85 species
General Characteristics:
Extremely simple! Few
dozen
cells forming a two-tissue layer triploblast.
o Elongate body with a ciliated epidermis.One class mostly invades gonads of marine invertebrates and when in host forms a multinucleated plasmodium body form.o No nervous, respiratory, circulatory, or digestive system
o All endoparasitic in marine invertebrates.
Phylogeny
Would be considered as diploblastic but:
Why doesn’t simplicity always imply that a group is an an early (primitive) evolutionary branch? ( i.e. what selective pressures lead to more simple body plans?)
Within the Mesozoa, there is still
controversy
on whether the two major groups are monophyletic, with some recent
molecular
evidence supporting common ancestry, though more recent analyses
suggesting that the Mesozoa should be divided into two new phyla.
Lecture Sources:
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