Any animal that moves, in the sense of covering the ground from A to B rather than just sitting in one place and waving its arms or pumping water through itself, is likely to need a specialised front end. It might as well have a name, so let’s call it the head. The head hits novelty first. It makes sense to take in food at the end that encounters it first, and to concentrate the sense organs there too—eyes perhaps, some kind of feelers, organs of taste and smell. Then the main concentration of nervous tissue—the brain—had best be near the sense organs, and near the action at the front end,
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