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26 Cards in this Set
- Front
- Back
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Phylum Platyhelminthes
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(the flat worms)
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Gen. characteristics of flat worms.
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-bilaterally symmetric
-three true tissue layers. -incomplete digestive system -no body cavity |
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how are Platyhelminthes classified?
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Classified according to their degree of adaptation to parasitic lifestyle
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What approximate percentage of flat worms are parasitic?
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>80%
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Acoelomate
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no body cavity but gut
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Eucoelomate
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Hollow body
Body cavity lined with mesoderm |
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Turbellaria
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-Free living
-Monozoic (flukes) flat shape |
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Trematoda
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-Endoparasitic
-Monozoic -Oral and ventral suckers -Diecious (m&f seperate) -indirect life cycles (including multiple hosts) and polyembryony |
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Monogenoida
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-Ectoparasitic flukes
-monozoic -Opisthaptors (hooks) |
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Cestodia
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-Obligate endoparasites w/indirect life cycles inclucing strobilation and (in some) polyembryony
-scolex -polyzoic with proglotids |
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General characteristics of phylum Mollusca
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-Bilaterally summetric
-tripoloblastic -eucoelomate -unsegmented protostomes enclosed in a mantle and (usually) a shell, with a radula for feeding. |
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how is phylum Mollusca classified?
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classified according to deviations from the putative ancestral plan
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What are the shells composed of?
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CaCO3 secreted by the mantle
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What is new with the phylum Mollusca?
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Respiratory and circulatory systems are new
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Primitive: Little Deviation Mollusca
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Monoplacophora
Aplacophora Polyplacophora |
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Modern more deviations for Mollusca
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Scaphopoda
Gastropoda Pelecypoda Cephalopoda |
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Gen. Characteristics of phylum Annelida (segmented worms)
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-Bilaterally symmetric
-triploblastic -Eucoelomate -segmented protostomes -transcutaneous respiration |
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How are Annelida classified?
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according to the presence or absence of parapodia (fleshy paddle-like appendages) and setae (bristles)
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Polychaeta
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-Have both parapodia and Setae
-Neanthes (the clam worm) |
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Oligochaeta
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have setae but lack parapodia
ex: (Earth worm) |
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Hirudinea
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leeches (have neither setae nor parapodia)
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Monoplacophora
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most like ancestor
one dorsal plate |
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polyplacophora
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-shell divided into 8 plates
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Aplacaphora
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shell absent
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Scaphopoda
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rolled up in tubular shell
tusk shells |
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Gastropodia
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show torsion
have spiral shell ex: snail Secondarily w?out a shell Ex: slug |
