2. Class Trematoda

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2. Class Trematoda 3. Class Monogenea

• Both are parasitic flukes
• Leaf-shaped flatworms
• Endoparasites
• Live in blood, intestines, lungs, liver, etc.
• Ectoparasites
• Live on external surfaces of aquatic hosts

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Structure of Flukes

• Anterior ventral suckers for attachment to host
• Nervous system like planarian
• Except NO eyespots
• Tegument outer layer that protects from hosts
  immune and digestive system

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Liver fluke
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Reproduction of flukes

• Most are hermaphroditic
• May release 10,000 eggs at a time!
• Complicated life cycle (p. 692)

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Life Cycle

• Primary host adult parasite gets nourishment
  from this host
• Sexual reproduction
• Intermediate host larvae derive nourishment here
• Asexual reproduction

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Fluke Diseases in Humans

• Swimmers itch minor skin irritation and
  swelling
• Small brown fluke in lakes (in Ohio)
• Dies within skin because humans are not ideal
  hosts

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Video 1
Video 2

• Schistomiasis (blood fluke) disease that causes
  tissue damage, bleeding, tissue decay and
  possible death
• Lungs, intestine, bladder, liver
• 200 million people affected worldwide

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Schistosoma

• Primary host
• human

Animation!

• Secondary or
• Intermediate host
• snail

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Swimmers itch
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4. Class Cestoda

• 5,000 species of tapeworms
• Can live in intestines of most vertebrates
• Enter through undercooked food with eggs or
  larvae (cyst)
• Symptoms of infection
• Digestive problems
• Weight loss
• Lack of energy
• anemia

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Structure

• Tegument to protect from host
• Also absorbs nutrients from host
• Scolex knob-shaped organ with hooks and suckers
  to attach to host
• Proglottids body sections after a short neck
• Up to 2,000 per tapeworm!

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Reproduction

• Hermaphrodites
• Each proglottid has ovaries and testes
• Filled with 100,000 eggs each!
• Eggs fertilized by sperm of different proglottid

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Life Cycle

• Cysts dormant larvae surrounded by protective
  covering in animal muscle