Motor Control in Annelids and Arthropods

In annelids and arthropods generally, individual metameric ganglia of the ventral nerve cord are capable of initiating and keep locomotor movement in the concerned segment. The suboesophageal ganglion exerts a control over these; actually it keeps the animal in hyper excited condition. The brain on the other hand exerts a moderating effect on the suboesophageal ganglion and suppresses the concerned centers in the suboesophageal ganglion. So, many of these animals show hyper excitability and an increased tendency for locomotion while their brain is removed. Conversely, when their suboesophageal ganglion is removed, locomotion is significantly inhibited or even stopped.