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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