Biol 11 Lesson 4 Feb 9 - Ch. 26 Flatworms

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Biology 11 …

Biology 11
Animal Biology unit - Invertebrates
Miller, K.R. & Levine, J. (2000). Biology (5th ed.). New Jersey: Prentice Hall.
Ch. 26: Sponges, Cnidarians, and Unsegmented Worms
pp. 570-575.

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  • 1. Homework from last class:
    • Complete Section Review 26-3 questions 1-5 (p. 569)
    • Complete Cnidaria crossword puzzle
    • Label and colour Cnidaria diagram handout — I will provide you with a new handout (due Tues, Feb. 15)
    • Read over class notes and check out the class blog:
    • http://msoonscience.blogspot.com/
    • Study for Quiz on Phylum Cnidaria next class!
  • 2. Cnidaria quiz
    • You have 10 minutes to write the quiz.
    • Good luck!
  • 3. Section Review 26-3 (p. 569):
    • What is a cnidarian? What kind of symmetry do cnidarians have?
    • A cnidarian is a soft-bodied aquatic animal exhibiting radial symmetry that has stinging tentacles containing nematocysts.
  • 4. Section Review 26-2 (p. 563):
    • 2) Give an example of each class of cnidarians.
    • 1) Class Hydrozoa: hydra, Portuguese man-of-war
    • 2) Class Scyphozoa: jellyfish
    • 3) Class Anthozoa: sea anemone, coral
    E.g. Hydra E.g. jellyfish E.g. Sea anemones and coral
  • 5. Section Review 26-3 (p. 569):
    • Describe the life cycle of a typical cnidarian.
    • A fertilized egg develops into a ciliated larva
    • The larva develops into a polyp
    • The polyp produces medusae asexually by budding
    • Eggs from female medusae are fertilized by sperms from male medusae
    1 2 3 4
  • 6. Section Review 26-3 (p. 569):
    • Discuss symbiotic relationships and other interactions between cnidarians and other living things.
    • Anthozoans provide habitat for photosynthetic protists or bacteria; they in turn provide food for the anthozoan.
    • Sea anemones and small fish are symbiotic.
    • Coral reefs provide a home
    • for many animals and help
    • protect shore habitats from
    • erosion.
  • 7. Section Review 26-3 (p. 569):
    • A medusa usually has specialized sense organs. It may also have nerves that are organized into rings that encircle its body and structures that control body contractions. Explain why a medusa needs a more complex nervous system than a polyp.
    • ( Hint: How does the lifestyle of a medusa differ from that of a polyp?)
    • Medusae are motile and thus need a nervous
    • system that can coordinate movement
    • and respond to stimuli quickly and effectively.
  • 8. Introduction to Planaria
    • http://www.youtube.com/watch?v=w0QzSYQGsnA
  • 9. Phylum Platyhelminthes: Flatworms Chapter 26: Sponges, Cnidarians, and Unsegmented Worms pp. 570-575
  • 10. Introduction to Flatworms
    • Phylum Platyhelminthes: platy = flat, helminth = worm
    • Simplest animals with bilateral symmetry
    • Body has 3 cell layers
      • ectoderm (outer)
      • mesoderm (middle)
      • endoderm (inner)
    • Show the beginnings of cephalization (i.e. a head)
    • Can be free-living or parasitic
    ectoderm mesoderm endoderm gastrovascular cavity
  • 11. Classes of Flatworms
    • Class Turbellaria
      • Free-living, usually small, freshwater
      • Predators or scavengers
      • Example member: Planaria
  • 12. Classes of Flatworms
        • 2) Class Trematoda (flukes)
      • Parasitic (internal parasites)  often infect blood and organs
      • Often have more than 1 host
      • Reduced digestive and nervous systems
      • Example member: blood flukes ( Schistosoma) ;
      • has 2 hosts (p. 573)
        • humans = primary host
        • snails = intermediate host
  • 13. Class Trematoda - blood fluke Schistosoma Intermediate host: snail primary host: human p. 573
  • 14. Classes of Flatworms
        • 3) Class Cestoda (tapeworms)
            • Long and flat parasites
            • Head is called scolex
            • Narrow neck region that divides to form proglottids (contain huge numbers of sperm and eggs)  p. 575 (beef tapeworm)
            • No digestive or nervous systems
            • Highly developed reproductive
            • system
    proglottid scolex
  • 15. Form and Function of Flatworms
        • Digestive system:
        • Gastrovascular cavity where food is broken down
        • Two-way digestive system
        • Food and wastes enter/exit the pharynx
    Pharynx = opening to the gastrovascular cavity e.g.Planaria
  • 16.
        • Respiratory system:
        • Circulatory system:
        • Excretory system:
        • Flame cells - primitive excretory structures that get rid of excess water
        • Metabolic wastes diffuse through the skin
    • No organized systems for these
    • O 2 , CO 2 diffuse through the ectoderm
  • 17.
          • Nervous system:
          • Fairly well-developed
          • Has primitive “brain” and
          • 2 ventral nerve cords
          • Ocelli (aka eyespots ) to
          • detect light/dark
        • Two auricles sensitive to touch
        • and chemicals
        • Musculoskeletal system:
        • Muscles and cilia on ventral surface for locomotion
    Planaria nervous system auricle
  • 18. If you cut a part off, it grows into a new worm!
  • 19. Planaria reproductive system
  • 20. La fin! Activity: Phylum Platyhelminthes Question Worksheet Phylum Platyhelminthes Colouring/Labeling Worksheet New Phylum Cnidaria Colouring/Labeling Worksheet
  • 21. Activity:
    • Work on the Platyhelminthes question worksheet
    • Work on the Platyhelminthes labeling/colouring worksheet
      • Make a legend of the colours you use on your diagram
      • e.g. Digestive system
      • Respiratory system
    • 3) Work on the new Phylum Cnidaria labeling/colouring worksheet.
  • 22. Homework for next class:
    • Complete the Platyhelminthes question worksheet
    • Complete the Platyhelminthes labeling/colouring worksheet
    • Complete the new Cnidaria labeling/colouring worksheet
    • Read over class notes and check out the class blog:
    • http://msoonscience.blogspot.com/
    • Study for Quiz on Phylum Platyhelminthes next class!