RAH_20Lec_204_20__20Acoels_2C_20Pseudoc

RAH_20Lec_204_20__20Acoels_2C_20Pseudoc - Hough Lecture...

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Hough Lecture Outline – Acoelomates, Pseudocoelomates 1 BILATERIA All remaining phyla are bilaterally symmetrical and triploblastic; three branches – Acoelomates, Pseudocoelomates, Coelomates ACOELOMATES worms with no body cavity; several minor phyla, one major phylum PHYLUM PLATYHELMINTHES Flatworms – planarians, flukes, tapeworms General characteristics flattened dorsi-ventrally hydrostatic support (no solid structures, as in all worms) gut incomplete – no anus (same as in Cnidarians) first phylum with some true organ systems, mostly primitive marine, freshwater, many parasitic Organ systems muscular – muscle cell bundles: longitudinal, circular, dorsiventral nervous – anterior ganglion, paired connected lateral nerves , simple eyes (ocelli) excretory – ciliated “flame” cells, tubules, excretory pores reproductive – complex sexual: testis & penis; ovaries , oviducts, genital pore hermaphroditic (both sexes in same individual), but cross fertilize digestive – incomplete: gastrovascular cavity (respiratory – diffusion only) (circulatory – gastrovascular cavity only)
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Hough Lecture Outline – Acoelomates, Pseudocoelomates 2 Classes of Platyhelminthes 1. Turbellaria – free living flatworms
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RAH_20Lec_204_20__20Acoels_2C_20Pseudoc - Hough Lecture...

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