Biol 11 Lesson 3 Mar 8 - Ch. 27 Annelida


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Ch 27 Mollusks and Annelids
pp. 594-600

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Biol 11 Lesson 3 Mar 8 - Ch. 27 Annelida

  1. 1. Homework from last class: <ul><li>Complete squid lab handout and analysis questions </li></ul><ul><li>Read Ch. 27-2 Annelids </li></ul><ul><li>Read over class notes and check out the class blog: </li></ul>
  2. 2. Phylum Annelida: Annelids Chapter 27: Mollusks and Annelids pp. 594-600
  3. 3. Top 10 Bloodsuckers: Leech <ul><li> </li></ul>
  4. 4. Introduction to Annelids <ul><li>Phylum Annelida – Latin annellus = “little ring” </li></ul><ul><li>Segmented worms </li></ul><ul><li>Bilateral symmetry </li></ul><ul><li>3 cell layers (ectoderm, endoderm, mesoderm) </li></ul><ul><li>Simplest phylum to have a coelom (fluid-filled cavity lined by mesoderm cells) </li></ul><ul><li>Annelids are considered to be related to mollusks because their larvae are similar (trochophore larvae) and they share similar developmental patterns </li></ul><ul><ul><li>Mollusks and annelids likely share a common ancestor (possibly worm-like) </li></ul></ul>
  5. 5. <ul><li>Comparative cross-sections: </li></ul><ul><li>Nematode Annelid </li></ul>Coelom Pseudocoelom (fluid-filled space) Coelom (fluid-filled space totally surrounded by mesoderm) endoderm mesoderm ectoderm
  6. 6. <ul><li>Most animals have tissues that are derived from 3 embryonic cell layers: </li></ul><ul><li>Ectoderm: develops into epidermis, ie. skin </li></ul><ul><li>Mesoderm: develops into muscle tissue and mesentary </li></ul><ul><li>Endoderm: develops into the tissue of the digestive tract ie. gut </li></ul>Coelom ectoderm mesoderm endoderm
  7. 7. <ul><li>The coelom is an important evolutionary advancement: </li></ul><ul><li>Separates the intestine from the muscles of the body wall by allowing for independent movement </li></ul><ul><li>Provides a space for a true circulatory system to develop </li></ul><ul><li>Coelomic fluid circulates O 2 /CO 2 , nutrients, and waste </li></ul><ul><li>* Mollusks also have a coelom but theirs surrounds only the heart not the entire intestine and internal organs.* </li></ul>Coelom
  8. 8. Classes of Annelids <ul><li>1) Class Polychaeta </li></ul><ul><ul><li>Bristly marine worms </li></ul></ul><ul><ul><li>Have paired appendages on each segment </li></ul></ul><ul><ul><li>Example members: sea mouse (p. 599) </li></ul></ul><ul><ul><li>2) Class Oligochaeta </li></ul></ul><ul><ul><li>Earthworms </li></ul></ul><ul><ul><li>Terrestrial; fertilize and aerate soil (produce “castings” </li></ul></ul><ul><ul><li>Example members: earthworms, tubifex worms </li></ul></ul>
  9. 9. Classes of Annelids <ul><li>3) Class Hirudinea </li></ul><ul><li>Leeches </li></ul><ul><li>Mostly freshwater </li></ul><ul><li>Have suckers at both ends; anticoagulants and anaesthetics to help suck blood </li></ul><ul><li>Example members: leeches </li></ul>
  10. 10. Form and Function of Annelids <ul><ul><ul><li>earthworm = representative annelid </li></ul></ul></ul><ul><ul><ul><li>Digestive system: </li></ul></ul></ul><ul><ul><ul><li>Complete digestive tract (mouth  anus) </li></ul></ul></ul><ul><ul><ul><ul><li>Mouth, pharynx, esophagus, crop (for storage), gizzard (for grinding), intestine, anus </li></ul></ul></ul></ul>Earthworm digestive system
  11. 11. <ul><ul><ul><li>Respiratory system: </li></ul></ul></ul><ul><ul><ul><li>Some aquatic ones have gills </li></ul></ul></ul><ul><ul><ul><li>Many (e.g. earthworms) exchange O 2 /CO 2 through the skin </li></ul></ul></ul>
  12. 12. <ul><ul><ul><li>Circulatory system: </li></ul></ul></ul><ul><ul><ul><li>Closed circulatory system – blood is always contained inside vessels </li></ul></ul></ul><ul><ul><ul><li>Have primitive “hearts” (earthworms have 5) to pump blood </li></ul></ul></ul><ul><ul><ul><li>Excretory system: </li></ul></ul></ul><ul><ul><ul><li>Nephridia (primitive kidneys) in each segment remove metabolic waste (nitrogen-containing wastes like NH 3 ) </li></ul></ul></ul>
  13. 13. <ul><ul><ul><li>Nervous system: </li></ul></ul></ul><ul><ul><ul><li>Fairly well-developed </li></ul></ul></ul><ul><ul><ul><li>Have a small brain, eyes or eyespots, statocysts, sensory tentacles, chemical receptors </li></ul></ul></ul>
  14. 14. <ul><ul><ul><li>Musculoskeletal system: </li></ul></ul></ul><ul><ul><ul><li>Longitudinal and circular muscles work together to propel worm (peristalsis) </li></ul></ul></ul><ul><ul><ul><li>Bristles present on ventral side for grip </li></ul></ul></ul>
  15. 16. Ecology of Annelids <ul><li>Earthworms are very important on land – they condition soil in 2 ways: </li></ul><ul><ul><li>Add nitrogen to the soil (in their “castings”) </li></ul></ul><ul><ul><li>They aerate the soil so oxygen gets in </li></ul></ul><ul><ul><li>In ocean, annelids are often the bottom of food web. </li></ul></ul>
  16. 17. Activity – Song, Story, Rap, or Poem! Serenade me!!
  17. 18. Activity Instructions: <ul><li>With a partner or working individually, create a song, story, rap, or poem that incorporates 10 characteristics or structural attributes and functions about Phylum Annelida. </li></ul><ul><li>Have fun with it! </li></ul><ul><li>*Note: If you choose a song, you must write down the tune that goes with your song. * </li></ul>
  18. 19. Homework for next class: <ul><li>Finish your Phylum Annelida song, story, rap, or poem (must submit with evaluation sheet) </li></ul><ul><li>Complete Annelida question worksheet </li></ul><ul><li>Complete earthworm colouring diagram </li></ul><ul><ul><li>You must include a key. Example: </li></ul></ul><ul><ul><ul><ul><ul><li>Excretory system </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li> Circulatory system </li></ul></ul></ul></ul></ul><ul><li>Read over class notes and check out the class blog: </li></ul>
  19. 20. Works Cited <ul><li>Images taken from the following sources: </li></ul><ul><li> </li></ul><ul><li> </li></ul><ul><li> </li></ul><ul><li> </li></ul><ul><li> </li></ul><ul><li> </li></ul><ul><li> </li></ul>
  20. 21. Works Cited <ul><li> </li></ul><ul><li> </li></ul><ul><li> </li></ul><ul><li> </li></ul><ul><li> </li></ul><ul><li> </li></ul><ul><li> </li></ul><ul><li> </li></ul>