01:119:116 Lecture Notes - Lecture 6: Symmetry In Biology, Radula, Medusozoa
22 Apr 2016
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Invertebrates - lack backbone; present on all main branches of animal phylogeny. Phylum porifera - to have pores ; sponges; basal taxon of all animals. No symmetry, tissues, organs (still have specialized cells: morphology. Spongocoel - central cavity water passes through; food particles filtered (not a digestive cavity) Choanocytes - collar cells, feeding cells of sponges; flagellated; collar of microvilli; ingest bacteria and food particles. Phylum cnidaria (basal taxon to eumetazoa: characteristics. A. 4. true tissues radial symmetry diploblastic cnidocytes - specialized stinging cells, unique to cnidaria: mostly marine (medusozoa jellies, anthozoa sea anemones & corals) Visceral mass - body mass, contains viscera (internal organs) Radula - belt of teeth in mouth area; scrapes up food (absent from bivalves) body wall, coelom, organs divided into segments (except digestive tract: major mollusk clades. Nudibranch - bright color poisonous bc steal stingers from cnidarians. A. 2. b) hinged shell (2 parts), no radula, suspension feeders includes clams, mussels, oysters, scallops.
