Mollusks Old

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Chapter 13 Section 1

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Mollusks Old

  1. 1. Mollusks Chapter 13 Section 1
  2. 2. A. Mollusks –soft bodied invertebrates with bilateral symmetry and usually one or two shells with organs in a fluid-filled cavity.
  3. 3. <ul><li>Thin layer of tissue called the mantle covers the body organs and secrete shell. </li></ul><ul><li>Mantle cavity (between soft body and mantle) contains gills. </li></ul><ul><li>For most mollusks, an open circulatory system moved blood through vessels into open spaces around body organs. </li></ul><ul><li>Well-developed head has a mouth and some sensory organs. </li></ul><ul><li>Underside is a muscular foot used to move. </li></ul>
  4. 4. <ul><li>Mollusks classified into three common groups based on shell presence, type and foot type. </li></ul><ul><li>1. Gastropods usually have a single shell. </li></ul><ul><li>a. Use a radula (a tongue-like organ with rows of teeth) to get food. </li></ul><ul><li>b. Have foot glands that secrete a layer of mucus for sliding. </li></ul><ul><li>c. Include snails, conchs, and garden slugs. </li></ul>
  5. 6. 2. Bivalves have a hinged, two-part shell and include clams, oysters, and scallops.
  6. 7. <ul><li>Cephalopods are most specialized and complex mollusks </li></ul><ul><li>a. Include squid, octopuses, and chambered nautiluses </li></ul><ul><li>b. Cephalopods have a well-developed head and many tentacles for capturing prey. </li></ul><ul><li>c. A closed circulatory system moves blood through the body in a series of closed vessels. </li></ul><ul><li>d. Cephalopods use jet propulsion to move at speeds of 6 m/s http://www.biology.ualberta.ca/courses.hp/zool250/animations/Squid.swf </li></ul><ul><li> </li></ul>
  7. 8. Among other uses, mollusks provide food for people and other animals as well as pearls and shells for jewelry and decorations.

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