[Campbell Biology P.741] Despite lacking a brain, how do cnidarians manage to coordinate mov... | Practice Question

Despite lacking a brain, how do cnidarians manage to coordinate movements and respond to stimuli from various directions?

  • A: Through a centralized ganglion that processes all sensory information.
  • B: By means of a noncentralized nerve net associated with distributed sensory structures.
  • C: Primarily through direct chemical communication between individual cells without any neural network.
  • D: They only respond reflexively to direct touch on their tentacles, lacking broader coordination.

Explanation

The text explicitly states: 'Cnidarians have no brain. Instead, movements are coordinated by a noncentralized nerve net that is associated with sensory structures distributed around the body. Thus, even though it lacks a brain, the animal can detect and respond to stimuli from all directions.' This directly supports option B.