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1 Phyla Hemichordata and Chordata Zoology- Mrs. Adams
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“Half Vertebrate” Hemichordates display some characteristics of invertebrates and vertebrates Coelomates Deuterostomes Have dorsal and ventral nerve cord, gill slits, postanal tail, NO NOTOCHORD 2
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Coelomates- true body cavity lined with mesoderm EX: all other animals
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Protostomes vs. Deuterostomes Zygote cleaves to become blastula and then forms gastrula. The blastopore of the gastrula can become either the mouth or the anus of the organism Protostome- Blastopore becomes the mouth. Ex-Annelids, Mollusks and arthropods Deuterostome- Blastopore becomes anus. Ex- echinoderms, hemichordates,chordates
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5 Embryonic Development Protostome –Blastopore becomes mouth Deuterostome –Blastopore becomes anus
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7 Phylum Hemichordata Three body regions –Proboscis –Collar –Trunk Deuterostome Gill slits Open circulatory system Dorsal and ventral nerve cord Ex. acorn worms
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8 Protostome=proboscis Collar trunk
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Lifestyle 9 coastal and deep ocean benthic (live in sand) Rarely seen by humans Size ranges – a few millimeters to 1.5 meters Use proboscis to decompose organic material in sand Release feces(poop) in coils Separate sexes release gametes
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