Procedure of evolutionary cephalization

Question

Using the examples of the invertebrate nervous systems how can the procedure of evolutionary cephalization be explained?

Answer 1

Considering the example of the invertebrates it is observed that evolution creates the increasing of complexity of organisms to be accompanied by the convergence of nervous cells to special structures for commanding and controlling: ganglia and brain. In simple invertebrates, such as cnidarians, the nervous cells are not concentrated however they are found dispersed in body. In platyhelminthes a beginning of cephalization with anterior ganglion concentrating neurons is already verified. In annelids and arthropods existence of a cerebral ganglion is evident. In cephalopod molluscs the cephalization is even greater and brain commands the nervous system.