Cephalization
Cephalization or Kephalisation (from the Greek κεφαλή kephale "head") is a phylogenetic development process, which for the majority of the representatives of Bilateria true. A part of the animal's body is morphologically separated from the rest of the body as a head . This is seen as a consequence of directional locomotion. In the area that precedes locomotion, there are light, tactile and chemoreceptors and structures for obtaining food, such as tentacles , mouth limbs, radulaeand teeth focused. The associated concentration of sensory cells and organs at the front end of an animal leads in a process of cerebralization (brain formation), which is in conformity with cephalization, to the concentration of nerve cells that process the sensory perceptions and trigger motor impulses. Sessile animals like polyps receive sensory perception from all directions. They are therefore built with radial symmetry and have no head. The same applies to echinoderms or mussels , which have become less mobile or sessile.
literature
- Lexicon of Biology . 3rd volume. Spektrum Akademischer Verlag., Heidelberg 2004, ISBN 3-8274-0328-6 .
- Robert Exner, Robert Routil (1958): The cephalization of vertebrates. Annals of the Natural History Museum in Vienna 62, pp. 25–56.
