Phylum Platyhelminthes

Phylum Platyhelminthes - Involving both vertebrate&...

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Phylum Platyhelminthes Thursday, October 25, 2007 10:20 PM I. Phylum Platyhelminthes a. Flatworms a. Characteristics i. Organ level of organization( says tissue on powerpoint) 1. Excretory 1. Nervous 1. Digestion a. Triplobastic i. Ectoderm (outside) i. Mesoderm i. Endoderm(inside) i. Bilateral symmetry 1. Cephalization 1. Flattened dorsoventrally Acoelomate (w/out a body cavity) Marine and freshwater environments Maintenance Functions Locomotion Wavy (ask?) Feeding Pharynx Ask? Means of gas exchange Diffuse oxygen Protonephridia Ask about this and osmoregualtion Osmoregulation Nervous system Ladder like Brain and nerve cords Elimination of wastes Does protonephridia go here along w/ osmoregulation? Circulatory, respiratory, and skeletal systems lacking Classes Class Turbellaria All free living Ex.) Planaria
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Reproduction Asexually Transverse fission Regenerate missing parts Sexual Cross fertilization Class Trematoda Flukes Anatomically close to Turbellaria Life cycle complex
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Unformatted text preview: Involving both vertebrate,& invertebrate hosts Life cycle of a Schistosome Fluke Humans definitive host Eggs are released into the bladder If eggs reach freshwater, hatches into swimming larvae called miracidia Burrows into aquatic snail Fork tailed larvae produced Leave snail, swim until encounter w/ human skin Attach to skin, enter body, and migrate to circulatory system where they mature Repeat Class Cestoidea Tapeworm Lack a mouth and digestive tract Absorb nutrients directly across their body wall Complex life cycles Adults contain proglottids Contains one or two complete sets of reproductive structures More Ask? Life cycle of beef tapeworm Most common tapeworm of humans Eggs in feces Eggs or proglottids ingested by cattle Hatches, and penetrates intestine to bloodstream Bloodstream to skeletal muscles Human eats infected meat Scolex attaches to human intestinal wall Tapeworm matures Repeat...
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Phylum Platyhelminthes - Involving both vertebrate&...

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