Discuss the evolutionary connection between bilateral symmetry and cephalization in animals
What will be an ideal response?
Answer: As organisms became more complex, this complexity was associated with an increase in cephalization. Very early animals had simple nervous systems with little centralization for processing information. Bilaterally symmetrical animals show a concentration of sensory and nervous tissue in the anterior parts of their bodies. With the evolution of bilateral symmetry, animals were able to move in a forward direction, using the sensory anterior end to locate food or sense threats. For example, arthropods, which are bilaterally symmetrical, have a distinct head region that processes extensive sensory information. Vertebrates show even more extensive cephalization. In mammals, for example, the brain and central nervous system control breathing, feeding, reflexes, thermoregulation, and movement.
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