Chapter 10 Cont.

Chapter 10 Cont. - • Sexual Reproduction o Cross...

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9/29/11 Chapter 10 Cont. Phylum Platyhelminthes (flat worms) Characteristics o Bilateral symmetry (typically exert cephalization) o Dorsoventrally flattened o Triploblastic (3 germ layers) o Acelomate (solid bodied animals) o Get incomplete or absent o Execretory/Osmoregulatroy structures called protonephridia o No respiratory organs/structures o No circulatory system o Anterior ganglia with longitudional nerve cords o Mostly monoecious or hermaphroditic o Free-living and parasitic species (no close relationship with another species) Class Tubellaria Free-living flatworms Marine and freshwater species Predators and scavengers o Many with a protrusible proboscis External surface usually ciliated o Cilia and muscular undulations-movement Sensory structure include ocelli and auricles Asexual Reproduction o Fission followed by regeneration
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Unformatted text preview: • Sexual Reproduction o Cross fertilization (reciprocal sperm exchange) Class Termatoda • Chinease Liver Fluke o A common parasite of humans in Asia o 30 million people are infected by eating raw or undercooked fish • Schistosoma Species o Blood flukes infect over 200 million people throughout the world Class Cestoidea (tapeworms) • As adults all reside in the digestive tract of vertebrates • No mouth, no digestive tract • Adult worms consist of repeated units called proglottids and the anterior holdfast structure is a scolex The beef tapeworm, Taeniarhynchus saginatus • People get these by cooking rare or uncooked meat Nemotodes • (pseudocoelomate) (false body cavity) Eucoelomates • True body cavity...
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Chapter 10 Cont. - • Sexual Reproduction o Cross...

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