Bio 2.2 Lab Exam 4: Cephalochordata

  1. How does Amphioxus move?
    It uses the notochord for stability and the muscles attached to it to more its caudal fin in a lateral motion.
  2. What do the dorsal and ventral fins do?
    Increase the propulsive force due to increased surface area.
  3. What are metapleural folds?
    Help move sand.
  4. What is the oral hood?
    A loose ciliated membrane with tentacles that surrounds the mouth.
  5. What organism is this?

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  7. What path does food and water take through aphioxus?
    • Food: Moves past the velum at the back of the throat, across the gill bars of the pharynx. Passes through the gill slits, back to the intestine and into the hepatic cecum, finally out the anus.
    • Water: Moves past the velum, across the gill bars and gill slits, and into the atrium, out the atriopore.
  8. What is the purpose of the endostyle?
    It secretes mucous to cover the gill bars and catch food as it moves through the gill slits.
  9. What is the purpose of the hepatic cecum?
    Secretes digestive enzymes to hydrolyze the polymers of food.
  10. Where are photoreceptors located on Amphioxus?
    The anterior end of the nerve cord.
  11. Where are the chemoreceptors located on Amphioxus?
    Near the oral hood.
  12. What type of circulatory system does Amphioxus have?
  13. How does the circulatory system work in Amphioxus?
    • Colorless blood is moved forward toward the pharyngeal basket where gas exchange occurs via peristaltic waves along its ventral aorta.
    • Blood moves up through the gill bars and then back along the dorsal aorta.
  14. What organism is this?

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Bio 2.2 Lab Exam 4: Cephalochordata