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Lecture 14, Ch. 32 - -2 layers no mesoderm bilateria are...

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Lecture #14 Date ______ Chapter 32 ~ Introduction to Animal Evolution
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Def: an•i•mal (n) Unique characteristics: Heterotrophic eukaryotes; ingestion Lack cell walls; collagen Nervous & muscular tissue Sexual; diploid; cleavage; blastula; gastrulation; larvae; metamorphosis Regulatory genes: Hox genes
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Animal phylogeny & diversity, I Monophyletic; colonial flagellated protist ancestor 1- Parazoa-Eumetazoa dichotomy : sponges (Parazoa)~ no true tissues; all other animals (Eumetazoa)~ true tissues 2- Radiata-Bilateria dichotomy : Cnidaria (hydra; ‘jellyfish’; sea anemones) & Ctenophora (comb jellies)~ radial body symmetry; all other animals~ bilateral body symmetry (also: cephalization)
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Animal phylogeny & diversity, II 3- Gastrulation : germ layer development; ectoderm (outer), mesoderm (middle), endoderm (inner); radiata are diploblastic
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Unformatted text preview: -2 layers; no mesoderm; bilateria are triploblastic-all 3 layers ■ 4- Acoelomate, Pseudocoelomate, and Coelomate Grades : triploblastic animals~ solid body, no body cavity called acoelomates (Platyhelminthes-flatworms); body cavity, but not lined with mesoderm called pseudocoelomates (Rotifers); true coelom (body cavity) lined with mesoderm called coelomate Animal phylogeny & diversity, III ■ 5- Protostome-Deuterostome dichotomy among coelomates : protostomes (mollusks, annelids, arthropods); deuterostomes (echinoderms, chordates) ■ a) cleavage: protostomes~ spiral and determinate; deuterotomes~ radial and indeterminate ■ b) coelom formation: protostomes~ schizocoelous; deuterostomes~ enterocoelous ■ c) blastopore fate: protostomes~ mouth from blastopore; deuterostomes~ anus from blastopore...
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