Flatworms aka Platyhelminthes

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Flatworms aka Platyhelminthes
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• Body style is very flat
• First group of critters to be made of THREE
  tissue layers
• Have true organs and organ systems

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• Most of these live in salt water but there are a
  few fresh water species
• Reproduce both sexually and asexually

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• First group of critters to have a type of brain
  called a ganglia
• Most have bilateral symmetry
• If you split the head of this critter in two- it
  will re-grow TWO heads last slide

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Flatworm/ Tapeworms

• Parasitic- need host to live in
• Live in the intestines of nearly every
  invertebrate
• Have long chain of sections called proglottids
  which hold 1000s of eggs

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Tapeworm scolex

• Attachment site for worm inside intestine

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Planarians/ Flatworms

• Free living
• Feed on small organisms and dead bodies of large
  organisms
• Both male and female organs (hermaphrodite)
• When there is little food, they break down their
  own organs and body parts for food
• Have a muscular tube called a pharynx that acts
  as a mouth

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Regeneration of Planaria