Cephalization

Cephalization or Zephalisation (from Greek: cephalic = head ) is a phylogenetic development process, which applies to the majority of the representatives of the Bilateria. Here, a part of the carcase is morphologically from the head from the rest of the body. This is considered as a consequence of the directional movement. In this light, tactile and chemoreceptors and structures for the acquisition of food, like tentacles, mouth limb Radulae and teeth are in the area preceding the movement, concentrated. The associated concentration of sensory cells and sensory organs at the anterior end of an animal leads to cephalization in a compliant ongoing process of Cerebralisation (brain training) to the concentration of nerve cells that process the sensory perceptions and motor impulses trigger. Sessile animals such as polyps receive sensations from all directions. They are therefore built radial symmetry and have no head. The same applies to echinoderms or molluscs, which have become secondarily little mobile or sessile.