The echinoderm has no brain located within its body. It has nerves running along its body. The nerves are located from the mouth to each arm; they then run from the arm to the body. The echinoderm has miniscule eye-pockets or opening that allows them to detect whether it is light or dark. Sensory cells send messages to the circumoral nerve ring. The tentacular cells send messages into the nerve ring. Branches of nerves along the body wall regulate the movement of the organism. The sensory cells along the body mostly help the echinoderm to gather information about its environment. This will help with its adjustment to its environment. A specific echinoderm is the starfish. The starfish has no brain. The nervous system of the starfish includes the radial nerve that runs along each ray and the circumoral nerve ring. These then connect to the radial nerve and the radial nerve is what processes all the information for the starfish. The starfish has a network of nerves that all connect together below its skin. These nerves allow the starfish to function.