Nervous system of Earthworm MCQ - Practice Questions with Answers

Neural system of Earthworm

Nervous system 

• In earthworm, the nervous system consists of ventral paired nerve which enlarges in each segment and form segmental ganglia
• The nerve cord in the region of 3rd and 4th segment (anterior region) bifurcates, encircles the pharynx laterally and connects to the cerebral ganglia dorsally in order to form a nerve ring
• Nerve ring is formed by the connection of cerebral ganglia with subpharyngeal ganglion along with circumpharyngeal connectives
• Presence of nerve ring is a characteristic of earthworm
• The cerebral ganglia and associated nerves in the nerve ring receive and process the sensory outputs which are converted into responses of the body

Sense organs 

• The sensory system does not have eyes but does possess light and touch receptor cells
• The sensory receptors of animal include three types of receptors i.e. tactile receptors, buccal receptors and photoreceptors
• Epidermal or tactile receptors- distributed on the lateral and ventral surface of the body and are related to touch. These help to feel the vibrations in the ground
• Buccal receptors- These are related to digestion and present in the buccal chamber
• Photoreceptors- These are related to light and are present on dorsal surface of the body