Cephalization is the concentration of sensory organs as well as a brain in a specified head area. The anterior, or head, is where the sensory cells and organs, clusters of nerve cells, and organs for ingesting food are located. The posterior is on the opposite end of the cephalized animal, which may have a tail.
Jellyfish do not have a brain, so they would not be considered cephalized.
I hope this helps.
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