2.10.10 - Porifera Cnidaria Platy- Annelida Mollusca...

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Unformatted text preview: Porifera Cnidaria Platy- Annelida Mollusca Nematoda Arthropoda Echino- Chordata helminthes dermata Lophotrochozoa Ecdysozoa Protistan ancestor Eumetazoa Bilateria Radiata Protostomia Parazoa levels of cell & tissue organization fundamental symmetry and number of germ layers Development patterns Cuticle presence or absence Deuterostomia Last major lineage to consider: Deuterostomes Like all protostomes, deuterstomes are triploblastic ; like many protostomes, they are eucoelomate . But they differ in the pattern of development: the anus ; mouth forms secondarily the mouth ; anus forms secondarily Blastopore forms: From gut, by enterocoely (archenteron outpocket pinches off to form coelom) Schizocoely (blocks of mesoderm split internally to form coelom) Origin of coelom Endodermal , from archenteron outpocket Ectodermal , from cells near blastopore Mesoderm formation Radial , indeterminate (cell fates established late in development) Spiral , determinate (cell fates established early in development) cleavage Deuterostomata Deuterostomata Protostomata Protostomata The deuterostomes: Echinoderms & Chordates The deuterostomes: Echinoderms & Chordates Deuterostome development : formation of mesoderm and coelom Blastopore forms anus, mouth forms secondarily , hence, deuterostomes ( deutero = second , stome = mouth ) Mesoderm begins to form from outpockets of the early gut: enterocoely ( from endoderm) The deuterostomes: Echinoderms & Chordates Deuterostome development : formation of mesoderm and coelom Blastopore forms anus, mouth forms secondarily , hence, deuterostomes ( deutero = second , stome = mouth ) Mesoderm begins to form from outpockets of the early gut: enterocoely ( from endoderm) Mesoderm eventually completely lines the coelom (eucoelomate) anus mouth Ectoderm Mesoderm Coelom (from gut: Enterocoely) Endoderm Gut lumen The deuterostomes: Echinoderms & Chordates Deuterostome development : formation of mesoderm and coelom Porifera Cnidaria Platy- Annelida Mollusca Nematoda Arthropoda Echino- Chordata helminthes dermata Deuterostomia Lophotrochozoa Ecdysozoa Protistan ancestor Eumetazoa Bilateria Radiata Protostomia Parazoa The deuterostomes: Echinoderms levels of cell & tissue organization fundamental symmetry and number of germ layers Development patterns About 7,000 species, all marine substrate dwellers (larvae planktonic). Adults sedentary or slow-moving. Unique features (besides deuterostomate development) are: Pentaradial symmetry . After coelom formation, larva goes through a bilaterally symmetric stage which develops asymmetrically . Internal (dermal) skeleton (endoskeleton) made of ossicles of CaCO 3 . Movable in some species (spines)....
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This note was uploaded on 04/03/2010 for the course BIO Bio 5b taught by Professor Chappel/douhan during the Winter '10 term at UC Riverside.

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2.10.10 - Porifera Cnidaria Platy- Annelida Mollusca...

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