Pila globosa Nervous system and Sense organ

Nervous system and Sense organ of  Pila globosa 

A] Nervous System of Pila globosa 

        The nervous system of Pila globosa consist of paired and unpaired ganglia with their commissures and connectives. Commissars are the nerves that establish a connection between the same ganglia, whereas connectives are the nerves that connect two different or different ganglia.

1] The nerves from the cerebral gangila go to the head, tentacles and eyes.

2] The buccal gangila send nerves to the buccal mass.

3] Nerves from the pendal gangila innervate the foot.

4] The pleural gangila go to the mantle, ctenidium and siphons.

5] The visceral ganglion nerves go to the intestine, kidneys and gonads. These nerves form the peripheral nerves.

B] Temporary mounting of sense organs & radula of Pila globosa

        In Pila globosa, the special organs of sense are single osphradium, paired eyes, statocysts & tentacles.

    1] Osphradium 

        The osphradium hangs from the mantle near the left pseudoepipodium. It is oval with 22 to 28 fleshy axes. It is a chemoreceptor and tests the stream of water that enters the mantle cavity through the left pseudoepipodium, it also exercises selection on the food taken in it. The evolution of the gastropod osphredium parallels that of the cetanidia, an osphredium in the primitive forms that is, for each tenidium, in the prosobranch that contains a cetanidium, there is only one osphredium; The osphredium disappears in those gastropods that have lost ctenidia, or have a reduced mantle cavity, or have become pelagic.

    2] Statocysts

        Located in the foot near each pedal ganglion lies a statocyst in a depression, It is a round capsule lined with epithelial cells & surrounded by connective tissue. The cavity of the capsule contains small calcified steatoconia. The statocysts receive nerves from pedal & cerebral gangila, they are organs of equilibrium and regulate the position of the snail.

    3] Radula

        Above and behind the odontophore is a sac-like radular sac which is the diverticulum of the oral cavity. The radular sac has transverse row of cells called odontoblasts. Inside the radular sac there is a radula which is characteristic of mollusca. The radula is composed of several transverse rows of horny teeth. Each row has seven teeth, two marginal and one lateral teeth on each side and a central or rachidian tooth in the middle, thus giving the formula 2, 1, 1, 2. The radula moves back and forth on the odontophore to rot the food. particles.