Multiple choice general knowledge Which is the only animal that doesn't have Brains Piranas Cucumber Fish Squit Star Fish Reveal answer Fill a bubble to check yourself D Correct answer Explanation Starfish (sea stars) do not have a centralized brain. They have a nerve ring and radial nerves but no brain. Piranhas, Cucumber Fish (likely sea cucumber), and Squit (likely Squid) all have brains or neural ganglia.