{"id":631,"date":"2018-12-29T16:45:34","date_gmt":"2018-12-29T23:45:34","guid":{"rendered":"https:\/\/blogs.ubc.ca\/mrpletsch\/?p=631"},"modified":"2020-02-27T20:01:15","modified_gmt":"2020-02-28T03:01:15","slug":"phylum-platyhelminthes-webquest-notes","status":"publish","type":"post","link":"https:\/\/blogs.ubc.ca\/mrpletsch\/2018\/12\/29\/phylum-platyhelminthes-webquest-notes\/","title":{"rendered":"Unit 5-3: Phylum Platyhelminthes – Webquest Notes"},"content":{"rendered":"

Phylum Platyhelminthes – Webquest Notes<\/h2>\n

Rather than me going through the notes and boring you, today you will be using this website to go over the notes, videos, and pictures at your own speed. You will gather notes through answering questions <\/strong>which gives you examples of questions I could ask on the simple invertebrates <\/strong>test while adapting my notes to fully address the question. Feel free to use other materials\/videos to explore these phylum and help clarify if you need. If you would like me to check on any of your answers\/diagrams, please let me know!
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Figure 1: Current Cladogram<\/figcaption><\/figure>\n

Platy<\/b><\/span>helminth<\/b>es -> \u201cFlat<\/b><\/span>\u201d \u201cWorm<\/b>\u201d<\/p>\n

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  • Appeared ~540 – 500 Million Years ago<\/li>\n
  • First animals with bilateral symmetry<\/b> and <\/b>cephalization<\/b> (<\/b>sense organs to the \u201cfront\u201d – development of brain)<\/li>\n<\/ul>\n
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    Figure 2: Flatworm diversity<\/figcaption><\/figure>\n

    A: Evolution of Body Plan<\/h2>\n

    1. Three tissue layers<\/b> – Endoderm, Mesoderm (muscle, organs), and ectoderm. They are\u00a0triploblastic.<\/strong><\/h5>\n
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    • Flatworms (like sponges\/cnidarians) are acoelomates<\/span>. This means they have no body cavity.<\/b><\/li>\n<\/ul>\n
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      Figure 3: Platyhelminthes Body Plan<\/figcaption><\/figure>\n

      Looking back: <\/em><\/strong>Tissue development continues (Porifera – no layers, cnidarians – 2 layers filled with jelly-like mesoglea), flatworms – 3 layers)<\/em><\/p>\n

      2. Cephalization <\/b>– Development and concentration of nerve tissue at one end of the body. Accessory organs for hearing, seeing, taste developed in this area.<\/h5>\n
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      • First animals to evolve a nervous system<\/b><\/li>\n
      • Eyespots <\/b>– Accessory organs used to detect intensity of light<\/li>\n<\/ul>\n
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        Figure 4: Planaria: a free-living flatworm<\/figcaption><\/figure>\n
        3. Bilateral symmetry – <\/b>The body plan can be divided in half making a right and left side that are mirrors of each other.<\/h5>\n
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        Figure 5: Bilateral Symmetry<\/figcaption><\/figure>\n
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        Figure 6: Comparing animal body plan symmetry<\/figcaption><\/figure>\n

        B. Feeding and Excretion<\/h2>\n
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        • Two-way digestive system <\/b>\u2013 <\/b>Food is ingested and waste is expelled through the pharynx.<\/li>\n
        • No mouth \u2013 a pharynx<\/b> is present on the underside of the animal that goes directly into the gastrovascular cavity<\/b>.<\/b><\/li>\n<\/ul>\n
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          Figure 7: Two-way digestive system<\/figcaption><\/figure>\n