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Organ System of Earthworm Homework Help

What is the organ system of an earthworm?

The circulatory system of earthworm: Closed circulatory system consisting of the heart, blood vessels, and capillaries with the blood completely confined to blood vessels and the heart.

The 4-6 segments comprise blood glands that secrete blood which is carried by the hemoglobin and dissolved in the blood plasma.

The blood vessels supply the gut, nerve cord, and the body wall through smaller contractions of the heart. Blood cells are capable of phagocytosis. The exchange of gases occurs through moist body surfaces into the bloodstream, thus making them come over the surface from time to time.

The excretory system in earthworms

Segmentally arranged coiled tubules called nephridia are the excretory organs of the earthworm. Nephridia function to regulate the volume and composition of body fluids. The structure of nephridium has a funnel that collects the excess fluids that are connected to a tubular part which throws out the wastes through a pore to the surface of the body wall into the digestive tube.

Three types of nephridia are seen

(i) Septal nephridia – present on both sides of the body from the 15th segment to the segment before the intestine opens up

(ii) integumentary nephridia – is seen attached to the body wall after the buccal cavity (segment 3) until the segment that opens to the body surface

(iii) Pharyngeal nephridia – the three paired tufts present in the 4th, 5th, and 6th segments of the body.

The nervous system of an earthworm 

The ganglia are arranged in each segment on the ventral pair nerve cord. The nerve cord begins in the 3rd and 4th segments, bifurcating and encircling the pharynx region, later joining the cerebral ganglia to form a ring on the dorsal side. This nervous system ring is responsible for integrating sensory inputs and commands the muscular responses of the body.

At the anterior end of the earthworm’s body, sensory organs for light, touch, and taste are present. Light sensitiveness and vibrations of the ground help the earthworm’s bodily activities. Chemoreceptors are specialized taste receptors present in the mouth of the earthworm.