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Published byEunice Chapman Modified over 9 years ago
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Flatworms-Platyhelminthes Least complex worm No body cavity (acoelomate) No respiratory system No circulatory system ◦All cells close to environment
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Flatworms Three Classes ◦Turbellerians (Planarian) ◦Cestoda (Tapeworms) ◦Trematoda (Flukes)
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Turbellarians Symmetry –Bilateral Structure ◦shovel head ◦flat body
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NERVOUS SYSTEM Mass of nerve cells [ganglia] form a simple brain Ladder-like arrangement throughout body Head sensitive to touch, smell, and taste Two eyespots sensitive to light
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REPRODUCTION Reproduction Asexual If cut into pieces – each piece will grow into new organisms Split themselves apart Sexual Produce both male and female sex cells (hermaphodidic) Cannot fertilize itself Lay eggs
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COOL! Planaria Regeneration An injury divided the head of this planarian in half. The two halves regenerated their lost parts. Eventually, the planarian will split lengthwise into two new planarians.
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DigestionExcretion
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The Monsters Inside Me
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Class Trematoda Parasitic flukes a) Liver flukes b) Schistomomes / intestinal flukes that suck blood c) use snails as an intermediate host sucker
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uterus testis ovary FLUKE – flat/parasitic Monoecious / hermaphroditic Class Trematoda
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suckers SEM image
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Intestinal Schistosomiasis 16 yr. Old boy Abdomen accumulates fluid- a body immune response to eggs embedded in tissues
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Intermediate host Definitive host Schistosomiasis
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Tapeworm showing proglottids Mature proglottids
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Tapeworm scolex (head ) light microscope hooks suckers Immature proglottids)
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Tapeworm scolex and hooks SEM image I love you
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Flea larva eats tapeworm eggs. Tapeworm larvae develop inside flea Worm grows in dog Dog eats infected flea Proglottids with eggs leave in wastes
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Rotifer video 2:30 Rotifer 1:30 Rotifer feeding
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Egg produced by adult exits in host in feces Host ingests eggs Hatch in host intestine Migrate to lungs as larva Molt in lungs Migrate to trachea, carried to stomach Adult stage in host intestine.
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Eggs ingested by host Organism matures in host large intestine Adult lives in host large intestine Adult migrates to perianal region to lay eggs at night Host gets eggs on fingers
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Eggs hatch in feces Develop into larva in the mud/soil Penetrate host skin through toes Enters circulatory system Migrates to lungs Matures and migrates to trachea Swallowed by host Adult stage in small intestine Eggs produced
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