BIOL 202 Lecture Notes - Lecture 5: Gastrovascular Cavity, Symmetry In Biology, Turbellaria
20 Jan 2016
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Worms: unsophisticated organ systems pseudocoelomates, can be acoelomate and coelomate, presence of gastrovascular cavity, no appendages, first appearance of bilateral symmetry, triploblastic tissues, protostome development, 3 phyla. Platyhelminthes: flat worms, triploblastic, acoelomate, unsegmented, class turbellaria. Protonephretic system for waste not a pump, no muscle. Uses cilia/flagella in flame cells to flow things around. Locomotion via cilia on the underside of the body. Blind gut branched digestive system, not flow-through. Diffuse memory neural net animals: class trematoda. Tegument shields worm from host"s defense system. Eggs are transition stage, picked up by intermediate invertebrate host (usually a mollusk) Food borne trematodiases human infection (56 million worldwide, second to malaria) Move into snail"s eyestocks, direct it towards light. Parasites often tissue specific host can have multiple independent parasites: class cestoidea. Live in digestive systems of vertebrates (endoparasitic) Has no digestive tract of its own. Scolex: a hook and sucker to attach itself.
