chordatesandhemichordata_1per-1

chordatesandhemichordata_1per-1 - RemainingDeuterostomes

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Remaining Deuterostomes tunicates are the nearest relative to the vertebrates Cephalochordata Craniata (vertebrates + hagfish) Urochordata
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Chordata = Urochordata , Cephalochordata, and Craniata Notochord Thin flexible rod that lies dorsal to the gut Adults may not have Single, dorsal tubular nerve cord. ther phyla may have nerve cords Other phyla may have nerve cords. Pharyngeal gill slits adults may not have Original purpose was filter feeding Feeding current generated by cilia Postanal tail Also may disappear before adulthood. Slide 1 (of 24)
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Urochordata (Tunicata) – ‘tailed’ chordates Tunicates, sea squirts, salps ~1300 extant species Bodies surrounded by a kind of jacket = tunic Connective tissue outside epidermis weird Very different from other chordates Three classes Ascideacea (ascidians and sessile tunicates) haliacea (pelagic tunicates salps) Thaliacea (pelagic tunicates, salps) Appendicularia (pelagic tunicates) Slide 2 (of 24)
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Sea squirts, or ascidians. litary, colonial, and mpound. Ascideacea So ta y, co o a ,ad co pou d •Single individual = zooid. Internal organs–few •Well developed hemal system •Most individuals have both male and female gonads •Nervous system with ganglia Most of internal space taken up by a mesh "basket" haryngeal basket Pharyngeal basket •Many rows of slits : derived from the pharyngeal gill slits Water is moved through by cilia Sheet of mucus to trap suspended particles.
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chordatesandhemichordata_1per-1 - RemainingDeuterostomes

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