Pila shows a well-developed nervous system. This nervous system will show 5 pairs of ganglia, the connectives and commisures and nerves.
1. NERVE GANGLIC
- Cerebral ganglia
- Pedal ganglia
- Visceral ganglia
- Pleural ganglia
- Supra and infra intestinal ganglia.
- On the dorso-lateral sides of the buccal mass cerebral ganglia are present. They are connected by cerebral commisures.
- On the ventrolateral sides of the buccal mass a pair pleural and a pair pedal ganglia are present. The cerebral ganglia and pleural ganglia are connected by cerebro-pleural connectives. The cerebral and pedal ganglia are connected by cerebro-pedal connectives.
- The two pedal ganglia are connected by pedal commisure. All these structures will form a nerve ring which looks like a square.
- At the junction of buccal mass and oesophagus two buccal ganglia are present. They are connected in the cerebral ganglia with connectives
- In the visceral mass two visceral ganglia are present. The pleural ganglia and visceral ganglia are connected by right and left pleuro-visceral connectives. From the right pleural ganglion a supra intestinal nerve will arise. It will travel over the oesophagus and is connected to the left pleuro-visceral connective. At this point, it form a supra intestinal ganglion.
- Left pleural ganglion gives a nerve which connects with right pleuro-visceral connective and a infra intestinal ganglion is formed. Thus these nerves will give '8' shaped structure.
- From cerebral nerve ganglia a number of small nerves will arise. They travel to tentacles, eyes, statocysts etc.
- From pleural tjerve ganglia nerves will arise and will innervate mantle.
- From visceral ganglia nerves will go to excretory organs, reproductive organs,
and to stomach.
Thus a well-developed nervous system is seen in the pila.