Question

write a short note on the nervous system of earthworm .

Answer 1

Answer:

Central nervous system

The CNS consists of a bilobed brain (cerebral ganglia, or supra-pharyngeal ganglion), sub-pharyngeal ganglia, circum-pharyngeal connectives and a ventral nerve cord. Earthworms' brains consist of a pair of pear-shaped cerebral ganglia.

Answer 2

Nervous system of Earthworm :

• The CNS (Central Atomic Number) consists of a nerve ring and a double ventral nerve cord .

• The nerve cord in the anterior region (3rd and 4th segments) bifurcates , laterally encircling the pharynx and join the cerebral gangilia dorsally to form a nerve ring .

• In each segment behind the fourth, the nervecord has a swelling formed of a pair of Segmental gangilia .

• The cerebral gangilia along with other nerve ring integrate sensory input as well as command muscular responses of the body .

• Sensory system does not have eyes but does posess light and touch sensitive organs (receptor cells)to distinguish the light intensities and to feel the vibrations in the ground.

• Worms have specialized chemoreceptors (taste Receptors) which react to chemical stimuli .

• These sense orgams are located on the anterior part of the worm.

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