WORMS

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WORMS

• PAGE 327-328

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Worms

• More complex
• Have 3 cell layers
• Specialized tissues and organs
• Categorized as
• flatworms
• roundworms
• segmented worms
• unlike sponges and coelenterates because
  they have a definite head and tail

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PHYLUM PLATYHELMINTHES

• Page 328-330
• Flatworms flat bodies / simplest worms
• Examples planaria / tapeworm / fluke

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Physical Characteristics

• Flat
• Bilaterally symmetrical
• Exhibit cephalization

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Cellular Structure

• 3 cell layers
• endoderm / mesoderm / ectoderm
• Organized cells/ tissues / organs / organ systems
  but..
• Lack respiratory and circulatory system
• .so movement by diffusion
• 4. One opening in digestive system located on
  ventral side in the center

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Food Getting

• Lives in water or inside another organism- this
  is the basis of how the organism gets food
• Free living Planaria (fresh water and salt
  water)
• -scavengers
• -simple digestive system (one opening)
• Explain mouth and pharynx extend from
  body suck up debris (like a vacuum cleaner)
• -food is digested in the intestine
• -waste? eliminated through the mouth (this
  is where food enters and leaves)
• -movement? crawl / swim - twists body
  back and forth
• when crawl a slimy mucus is left and cilia
  helps it slide through the mucus

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• Parasite tapeworm
• page 329 dog tapeworm (lives inside the bodies of
  other animals
• Tapeworm attaches to inside wall of intestines by
  using hook / suckers (scolex)
• No mouth or digestive track so.
• Absorbs digested food through skin of the body of
  the host

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TAPEWORM FLUKE
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NERVOUS SYSTEM

• Simple brain and some memory storage
• Explain???
• Eyespots photoreceptors
• does not form images but senses light

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REPRODUCTION

• Hermaphroditic both male and female
• Sex organs in one organism
• -Sexually each fertilize each other / an
  exchange of egg and sperm
• -Asexually regeneration only

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EXAMPLES

• Free-living Planaria
• Parasite
• Tapeworm
• Flukes shaped like a leaf
• complex life cycle
• Example Sheep Liver Fluke
• Schistomasis

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Planaria Anatomy