s09112lect7

s09112lect7 - Animals Eukaryotic Diversity Kingdom Animalia...

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K. Animalia 1 BIOL 112 Eukaryotic Diversity: Kingdom Animalia BIOL 112 Animals Heterotrophic, multicellular forms expressing more than one tissue type Usually highly differentiated tissues and organs Usually motile; no cell walls (glycocalyx instead); elaborate extracellular networks of the protein collagen Diploid-dominant life cycles Fertilized eggs develop into adults through complex, stereotyped sequence of embryological phases At least 30 phyla Ancient group with diverse fossil record Approximately 1.5 x 10 6 described species; possibly up to 10 7 total. BIOL 112 Traditional Morphological Body Plan Criteria for Organizing Animals Symmetry of Body Plan Embryological Pattern of Development Organization of Tissue Layers in the Body Digestive Tract Organization Circulatory System BIOL 112 Primitive plan (a few phyla) Advanced plan (most phyla) BIOL 112 Body Plan Bilateral Symmetry implies several axes: Anterior/Posterior (A/P) Dorsal/Ventral (d/v) What are molecular bases of these axes as they develop during embryogenesis? How did these control systems evolve? BIOL 112 Distinctive animal embryological development sequence Gastrulation begins the formation of the digestive system
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K. Animalia 2 BIOL 112 What does Blastopore become? Mouth — Protostome Anus — Deuterostome Layers of tissues (germ layers) in embryo a. Ectoderm b. Mesoderm c. Endoderm Three: advanced phyla BIOL 112 Body Plan Characters: Three tissue layers in body plan Coelom or not? True coelom or pseudocoelom? BIOL 112 BIOL 112 Digestive System “One opening, two way.” Single opening to gastrovascular cavity serves as both mouth and anus. “Batch processing:” one meal must be completely digested and eliminated before next meal can enter. Less efficient; primitive “Two opening, one way.” Both mouth and anus openings to system. Food moved/processed in one direction. “Assembly line processing:” animal can eat sequential meals without stopping. Advanced; most phyla have this Animal organization: “tube within a tube” BIOL 112 Phylogenetic Trees Suggested evolutionary patterns, depending on the sources of information used to construct the criteria for the branch points Body plan (morphology) and development (embryology)-based scheme Molecular sequence-based scheme Schemes produced are different in some details BIOL 112 Agreement of Schemes All animals have a common ancestor Sponges are barely multicellular — extremely primitive animals Eumetazoa (all animals except sponges) have true tissues Most animals are Bilateria (bilateral symmetry: this excludes sponges, cnidarians, ctenophores and Trichoplax ) Vertebrates and a few other phyla belong to the deuterostomes Most invertebrates belong to the protostomes
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K. Animalia 3 BIOL 112 Traditional animal kingdom phylogeny, based on body plans and embryology criteria discussed above BIOL 112 Animal kingdom phylogeny, based on molecular data BIOL 112
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This note was uploaded on 10/20/2009 for the course BIOL 112 taught by Professor Vaughn during the Spring '08 term at Texas A&M.

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s09112lect7 - Animals Eukaryotic Diversity Kingdom Animalia...

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