The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain and spinal cord. The CNS is so named because the brain integrates the received information and coordinates and influences the activity of all parts of the bodies of bilaterally symmetric animals—i.e., all multicellular animals except sponges and jellyfish. It consists of a large nerve running from the anterior to the posterior, with the anterior end is enlarged into the brain. Not all animals with a central nervous system have a brain, although the large majority do.