Practice question

Cephalization defined as evolutionary trend concentrating neurons, sensory organs and feeding apparatus at anterior end forming head or brain, achieves maximal development in bilaterally symmetrical animals displaying pronounced anteroposterior polarization, active motility and predatory habits such as arthropods, cephalopods and vertebrates. Bilaterality imposes directionality requiring anterior integration of photoreception, chemoreception and mechanoreception. Radially symmetrical cnidarians maintain nerve net without centralized brain, asymmetrical sponges lack neurons entirely, sessile forms reduce need for cephalic dominance due to nondirectional interaction, thus bilaterians showcase advanced cephalization.