[Campbell Biology P.1135] According to Figure 49.2 and the accompanying text, which animal li... | Practice Question

According to Figure 49.2 and the accompanying text, which animal listed below exhibits a nervous system characterized by cephalization, a small brain, and longitudinal nerve cords forming its CNS, but lacks segmental ganglia?

  • A: Leech (annelid)
  • B: Insect (arthropod)
  • C: Planarian (flatworm)
  • D: Sea star (echinoderm)

Explanation

The text states that in nonsegmented worms such as the planarian Figure 49.2c , 'a small brain and longitudinal nerve cords constitute the simplest clearly defined CNS.' Planarians do not have segmental ganglia.