Hydra and jellyfish are multicellular organisms that are radially symmetrical. This means they look identical when split at any point around a circle, looking downwards onto their body plan.
They have very basic nervous systems and digestion, and the aqueous medium they reside in supports their bodies.
They don’t have a centralised system with a brain or a spinal cord. Their neurones are simply spread across their body and interconnected, producing signals that are not traceable depending on the location of the…