Biol 11 Lesson 3 Feb 7 -  Ch. 26 Cnidarians
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Biol 11 Lesson 3 Feb 7 - Ch. 26 Cnidarians



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. 564-569.



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    Biol 11 Lesson 3 Feb 7 -  Ch. 26 Cnidarians Biol 11 Lesson 3 Feb 7 - Ch. 26 Cnidarians Presentation Transcript

    • Homework from last class:
      • Complete Section Review 26-2 questions 1-3 (p. 563)
      • Fill in and colour the sponge diagram worksheet
      • Read over class notes and check out the class blog:
      • Study for Quiz on Phylum Porifera next class!
      • Return Field Trip form by Feb. 7 – Vancouver Aquarium!
      • Bring pencil crayons to class for all the colouring ahead! 
    • Sponge quiz
      • You have 10 minutes to write the quiz.
      • Good luck!
    • Section Review 26-2 (p. 563):
      • How do sponges differ from other animals? How do they feed, respire, and eliminate wastes?
      • Sponges:
        • do not have a mouth or digestive tract (gut)
        • no true tissue layers (endoderm, ectoderm, mesoderm) or organ systems
      • Feed: Collar cells catch food particles and engulf them; amoebocytes take food particles from the collar cells and carry them to other parts of the sponge.
      • Respiration and excretion: The current of H 2 O that flows through the body of a sponge delivers O 2 to the cells and removes CO 2 and cellular wastes.
    • Section Review 26-2 (p. 563):
      • 2) How are sponges providing useful to medical science?
      • Sponges produce chemicals that can be used to fight bacteria, viruses, and other disease-causing microorganisms.
    • Section Review 26-2 (p. 563):
      • 3) Why are sponges thought to be an evolutionary dead end?
      No other groups of organisms have evolved from sponges.
    • Warm-up: The Box Jellyfish
    • Phylum Cnidaria: Jellyfish, Sea Anemones, and Corals Chapter 26: Sponges, Cnidarians, and Unsegmented Worms pp. 564-569
    • Introduction to Cnidarians
      • Soft-bodied animals
      • Radially symmetrical
      • Body has 2 cell layers (ectoderm and endoderm) separated by a layer of jellylike (mesoglea)
      • Have stinging tentacles arranged in a circle around mouth
      • Most have life cycles that include 2 stages :
        • Polyp
        • Medusa
      gastrovascular cavity endoderm mesoglea ectoderm
      • Medusa
      • free-floating
      • motile
      • Polyp
      • a ttached
      • sessile
    • Both forms have a gastrovascular cavity with only one opening  food enters the same hole that wastes go out! (a two-way digestive system)
    • Classes of Cnidarians
      • Class Hydrozoa
        • Mostly polyps ; short medusa stage
        • Often live in colonies , where specialized polyps perform particular functions
        • Example members: hydras (small, freshwater), Portuguese man-of-war (huge, marine; colonial)
          • 2) Class Scyphozoa (jellyfish)
        • Medusa is dominant stage ;
        • very short polyp stage
    • Classes of Cnidarians
          • 3) Class Anthozoa (sea anemones and corals)
              • Polyps only , no medusa stage
              • Corals create protective “cups”; anemones don’t
              • Some corals are reef building and are ecologically important
    • Form and Function of Cnidarians
          • Digestive system:
          • Gastrovascular cavity is where food is broken down
          • Food is absorbed and further digested by the cells that line the gastrovascular cavity (gastroderm (endoderm) cells)
          • Cnidoblast cells (in tentacles) contain nematocysts  poison darts that spring out when touched and paralyze prey
            • Tentacles then pull food into mouth
    • Form and Function of Cnidarians
          • Respiratory system:
          • Circulatory system:
          • Excretory system:
          • O 2 , CO 2 , and wastes get in and out of cells by diffusion through gastrovascular cavity and epidermis (ectoderm) .
          • Direct exchange with surrounding water.
      • No organized systems for any of these
      • No need since cnidarians are only a few layers thick
      for metabolic waste
    • Form and Function of Cnidarians
    • Obelia life cycle
    • Life cycle of a Cnidarian
    • Ecology of Cnidarians
          • Sea anemones and small fish are symbiotic
          • Coral reefs are a major habitat for many organisms They also protect the land from erosion
            • Coral reefs are very sensitive to pollution!
            • Some cnidarians are used in medical research (toxins)
    • Fertig! Activity: Sponge and Cnidaria Crossword puzzle Cnidaria colouring worksheet
    • Activity:
      • Work on the Sponge and Cnidaria Crossword Puzzle – vocabulary review from the last 2 classes
        • Helpful for homework and quizzes!
      • Colour your Cnidaria worksheet according to the colour coding scheme for body systems on the Animalia Unit outline
    • Homework for next class:
      • Complete Section Review 26-3 questions 1-5 (p. 569)
      • Complete Cnidaria crossword puzzle
      • Label and colour Cnidaria diagram handout
      • Read over class notes and check out the class blog:
      • Study for Quiz on Phylum Cnidaria next class!