9. Annelids II - 1 Phylum Phylum Annelida Annelida...

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Unformatted text preview: 1 Phylum Phylum Annelida Annelida "little rings" "little rings" Segmented worms Segmented worms Coelom Coelom- True True coelom coelom , lined by mesoderm , lined by mesoderm Triploblastic Triploblastic , Organ Grade , Organ Grade Segmentation Segmentation Metamerism Metamerism- serial repetition of parts serial repetition of parts Metamerism : serial repetition of parts Seen in 3 major groups Annelids : segmentation of coelom by transverse septae Arthropods : limb and musculature segmented Chordates : body wall musculature Chordate metamerism convergent with Ann. and Arth. Ann. and Arth. - may be convergent as well historically thought to be homologous, but new phylogenies more confusing. 4 Major Taxa you need to know: Class Polychaeta Class Clitellata Subclass Oligochaeta Sublcass Hirudinoidea Class Polychaeta: Many (poly) chaetae on parapodia, no clitellum, most separate sexes, often indirect development with trochophore larvae Marine mainly Class Clitellata No parapodia, reduced or absent chaetae, hermaphroditic, complex reproductive system with clitellum, direct development Subclass Oligochaeta: No parapodia Few chaetae (oligo) Freshwater and marine, terrestrial Subclass Hirudinoidea: No parapodia No chaetae Lack internal segmentation walls Freshwater and marine, terrestrial General Body Plan Presegmental Prostomium - eyes, antennae, palps, ganglia Postsegmental tail - anus Trunk Segments - In Each Segment: body wall muscles gut (diverticula) circulatory system nervous system reproductive system Segments : similar, repeated = HOMONOMOUS Prostomium : presegmental, w/ ganglia, sensory structures Pygidium : postsegmental 2...
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9. Annelids II - 1 Phylum Phylum Annelida Annelida...

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