Question

Which of the following is true in case of Pheretima?

• A. They have eyes that sense light
• B. The sense organs are located in the posterior part of the body
• C. The central nervous system comprises of nerve ring only
• D. The nerve ring is present in the 3rd and 4th segments

Answer 1

The correct option is D The nerve ring is present in the 3rd and 4th segments

The earthworm does not have eyes. It has light and touch sensitive receptors to help it distinguish light intensities and feel vibrations in the ground. They also have specialised taste receptors which respond to chemical stimuli. These sense organs are located in the anterior part of the worm.
The central nervous system in earthworm comprises the ventral nerve cord and the nerve ring. The nerve ring is present in the 3rd and 4th segments. The nerve plexus is a network of nerves that carry sensory inputs and muscular responses from the cerebral ganglion to various parts of the body. Nerve plexus is part of the sympathetic nervous system.