Lecture 15 Outline Chapter 33

Lecture 15 Outline Chapter 33 - Crampton. Bio II Lecture...

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Crampton. Bio II Lecture Handouts Lecture 15 Lecture 15: Invertebrates II September 2011 Slide 01: 1. Diploblastic body plan, true tissues 2. Radial symmetry 3. Bilaterial symmetry, triploblastic body plan. The bilateria are all TRIPLOBLASTS Slide 02: The acoelomates: Platyhelminths. Slide 03: Phylum: Platyhelminthes Bilateral, triploblastic, acoelomate “Flatworms” 1
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Crampton. Bio II Lecture Handouts Lecture 15 incomplete gut No circulatory system Hermaphroditic (recombination only when 2 individuals mate) Nervous system: more complex and cephalized than nerve-net of Cnidaria 4 groups: Turbellaria, Monogenea Trematoda, Cestoda Slide 04: Turbellaria. e.g. Planaria. Fig. 33.10: Mouth/Pharynx only (no anus): Cephalized nerve net. Marine flatworm. Slide 05: Amazonian turbellaria. Slide 06: Monogenea. Parasites Suckers attach to host Mongenea : fish ecto-parasites Trematoda : vert. endoparasites (attach to host organs), life-cycle requires multiple hosts (need immunological camouflaging - Mimic surface protein of host/s) e.g. Trematode: Schistosoma mansoni: Male and female live together. Slide 07-08: Trematoda. Life cycle of Schistosoma mansoni: Fig. 33.11. Slide 09: Schistosomiasis: “bilharzia”, “snail fever” chronic illness – damages internal organs. S. mansoni. From Africa. 2
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Crampton. Bio II Lecture Handouts Lecture 15 Also in S. America: associated with gold mining areas Slide 10: Cestoda: Parasites of intestines (mostly vertebrates) Scolex attaches to intestinal lining, absorb nutrients Each segment termed a proglottid (egg sac). Proglottids excreted and eggs hatch into larvae that encyst in tissue of secondary host. Slide 11: PARASITOLOGISTS DON’T EAT SUSHI: 8.8 m tapeworm in a Tokyo Museum: large cestode ingested by a man who ate uncooked fish (Sushi) Slide 12: The Pseudocoelomates: rotifers and nematodes Slide 13: Note differences between morphology and molecular-based tree. Rapidly changing taxonomy. Last version of text book had pseudocoelomates as a monophyletic group. Slide 14: 3
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Crampton. Bio II Lecture Handouts Lecture 15 Phylum: Rotifera. Complete alimentary canal – separate mouth and anus Small, aquatic and free-living, Corona - ciliated discs (feeding) Asexual reproduction by parthenogensis (females only, develop from un-fertilized eggs) An ancient asexual scandal: Bdelloid Rotifers: Over 300 species, Cloned females – asexual reproduction only. For 85 mllion years. This is very unusual. Only having asexual reproduction is rare
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Lecture 15 Outline Chapter 33 - Crampton. Bio II Lecture...

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