Feb 20 Intro Animalia porifera and cnidaria 2009

Feb 20 Intro Animalia porifera and cnidaria 2009 -...

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Introduction to the Animal ‘Kingdom’ KEY FEATURES “Typical” Animal Traits Heterotrophic / ingestion Multicellular “ Metazoa ” – Monophyletic (?) Tissue/organ level of construction Tissue fates embryonically determined A tissue-level nervous system Presence of centriole => organizing structure for mitosis 1) Symmetry which way to face? ‘Radial’ Radiata Bilateral Bilateria Cephalization 2) Embryology/Tissues Blastula => grastrulation => two layered Gastrula Tissues Ectoderm; Ectoderm; Mesoderm Cavities – Where the gut fits Acoelomate => No body cavity e.g. flatworms Pseudocoelomate => Gut not lined with mesoderm Coelomate => Gut lined with mesoderm Development Protostome => Blastopore becomes the mouth Determinate spiral cleavage Mesoderm derived from Blastopore lip Schizocoelous Duterostome => Blastopore becomes the anus Indeterminate radial cleavage Mesoderm derived from wall of the developing gut Enterocoelous
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PHYLUM PORIFERA True multicellularity Distinct cell types with specific functions Choanocytes - collar cells Scleroblasts - secrete skeletal elements Pore cells - control water flow
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Feb 20 Intro Animalia porifera and cnidaria 2009 -...

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