Jellyfish are remarkable creatures. Did you know that jelly fish are 94% to 98% water and that they are older then dinosaurs? Their bodies are radial symmetry which means that if you were to cut one in half you would get two identical halfs. This is because all their body parts extend from one central point.
Jellyfish apart from having no brain also lack bones and a heart. Compared to most other animals they are a relatively simple and primitive life form. In place of a brain, Jellyfish have rudimentary sensory nerves at the base of their tentacles to see light, orient themselves and detect smells. Jellyfish prove that a brain and heart are not necessary to support life.