Cephalization
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Cephalization concentrates sensory organs and a nerve-cell cluster at an animal's anterior end, a trend associated with bilateral symmetry and directional movement.
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A planarian flatworm's head carries eyespots and a concentrated ganglion, letting it sense its environment before the rest of its body arrives.
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Cephalization correlates with directional movement, not with any ranking of a lineage's evolutionary sophistication.