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31 Cards in this Set
- Front
- Back
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Phylum Platyhelminthes
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"flat worms" / contains over 34,000 species
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bilaterally symmetrical
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only dividing one way
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incomplete digestive system
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use a pharynx for eating and expelling
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monoecious
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flatworms are monoecious meaning they have characteristics of male and female
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Planarians (Turbellarians)
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free-living bottom dwellers in freshwater and marine environments
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duogland system
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system of adhesive glands and releaser glands in planarians
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adhesive glands
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open to the epithelial surface and produce a chemical that attaches part of the turbellarian to a substrate
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releaser glands
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secrete a checmial that dissolves the attachement as needed
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circular muscle
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the outer layer of muscle just below the epithelium that help move worm
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longitudinal muscle
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the inner layer of muscle just below the epithelium
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Planarians nutrition
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have a mouth opening near pharynx
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planarian mouth
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near pharynx
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digestion
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partially extracellular / have digestive cavity
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planarians as predators
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they are scavengers / carnivores and feed on small, live invertebrates or scavenge on larger, dead animals / some are herbivores
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ocelli
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most turbellarians have two simple eyespots / they orient the animal to the direction of light
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reproduction in planarians
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many reproduce asexually by transverse fission and binary fission / turbellarians are monoecious / normally reproduce sexually by cross fertilization to preserve genetic diversity
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Flukes (Trematoda)
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8000 species / wide, flat shape / almost all adult flukes are parasites of vertebrates / many of great economic and medical importance
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endoparasites
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flukes feed on host cells and cell fragments
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tegument
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the external epithelial covering in cestodes, trematodes, and flukes
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fluke digestion
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incomplete digestion
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fluke morphology
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they have an oral sucker near mouth and tegument
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fluke reproduction
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monoecious
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fluke life cycle
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complex - lays eggs, then goes to intermediate host and then to final host and restarts process
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Chinese liver fluke
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example of life cycle
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Tapeworms (Class Cestoidea or Cestoda)
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most highly specialized class of flatworms / 3500 species of endoparasites / usually reside in vertebrate digestive system
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tapeworm body
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scolex
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the one end of body that contains circular or leaflike suckers and sometime a rostellum of hooks / with scolex, the tapeworm firmly anchors itself to the intestinal wall / no mouth is present
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proglottids
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function primarily as reproductive units
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strobila
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consists of a series of linearly arranged proglottids
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tapeworm digestive
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digestive system absent / absorms nutrients through tegument / the tegument even absorms some of the host's enzymes to facilitate digestion
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tapeworm reproduction
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monoecious / produce a large number of eggs / each proglottid contains one or two complete sets of male and female reproductive organs
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