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What worms have a ventral nerve cord?

What worms have a ventral nerve cord?

Encyclopædia Britannica, Inc. The most primitive annelids have a pair of ventral nerve cords joined by transverse connectives; the most advanced forms have the cords fused to form a single cord.

Where is the ventral nerve cord located in an earthworm?

The ventral nerve cord (formed by nerve cells and nerve fibers) begins at the sub-pharyngeal ganglia and extends below the alimentary canal to the most posterior body segment.

What does the ventral nerve cord do in a grasshopper?

The first ventral ganglion is used primarily to control movement of the mouth. The segmental ganglia throughout the length of the grasshopper are connected to the first ventral ganglion by a double nerve cord and serve to coordinate local activities.

What is the ventral of an earthworm?

The bottom-side of an animal is called the ventral surface. In many animals, the ventral surface is a lighter colour or shade than the dorsal surface. The periproct is the last segment of an earthworm. Each segment, except the first and last, have tiny bristle-like structures called setae.

Does the brain attached to the ventral nerve cord?

The earthworm’s ‘brain’. The cerebral ganglion is connected to a ventral nerve cord that runs the length of the body. Each segment is connected to this cord, allowing earthworms to move and respond to light, touch, chemicals, vibrations and more.

What is the meaning of ventral nerve cord?

: a chain of connected segmental ganglia lying against the body wall in the body of an arthropod or annelid.

Is the nerve cord on the dorsal or ventral side in an earthworm?

Cerebral ganglion The earthworm’s ‘brain’. Earthworms have a simple nervous system. The cerebral ganglion is connected to a ventral nerve cord that runs the length of the body. Each segment is connected to this cord, allowing earthworms to move and respond to light, touch, chemicals, vibrations and more.

Is nerve cord and spinal cord same?

In vertebrates, the dorsal nerve cord is modified into the central nervous system, which comprises the brain and spinal cord. Dorsal means the “back” side, as opposed to ventral which is the “belly” side of an organism.

Where is the nerve cord of an earthworm located?

Earthworms have a simple nervous system. The cerebral ganglion is connected to a ventral nerve cord that runs the length of the body. Each segment is connected to this cord, allowing earthworms to move and respond to light, touch, chemicals, vibrations and more. Also, where are the seminal vesicles located in an earthworm?

How is the plexus of an earthworm connected?

This behaviour is a reflex and does not require the CNS; it occurs even if the nerve cord is removed. Each segment of the earthworm has its own nerve plexus. The plexus of one segment is not connected directly to that of adjacent segments. The nerve cord is required to connect the nervous systems of the segments.

Where do sensory fibers start in an earthworm?

Sensory fibers start from a sensory cell or receptor organs in the epidermis and terminate in the ventral nerve cord in fine branches. Near the branches in the cord, and forming a synapse with them, arise similar branches of motor fibers which run outward and terminate in muscles.

How many nerves does the ventral nerve cord give off?

Each segmental ganglion of the ventral nerve cord gives off 3 pairs of lateral nerves. One pair in front and 2 pairs behind the row of setae, they supply the various parts of the segment in which the ganglia are situated.