Here's why:

* Cephalization refers to the concentration of sensory organs, nervous control, and often a mouth at the anterior (head) end of an organism.

* Nervous system is responsible for receiving sensory information, processing it, and coordinating responses.

Cephalization allows for:

* Efficient processing of sensory information: Having sensory organs concentrated in the head allows for better detection and interpretation of stimuli from the environment.

* Targeted responses: A centralized nervous system enables quicker and more focused responses to environmental cues.

* Enhanced mobility: The development of a head allows for directional movement and exploration of the environment.

This concentration of nervous tissue and sensory organs in the head is a key characteristic of bilaterally symmetrical animals, especially those with active lifestyles.