Haritha,Subject Matter Expert at Edumarz
Solution:
(i)The excretory organ of an earthworm is termed the nephridium. They are seen as segmentally arranged coiled tubules called nephridium.
(ii)There are three types of nephridia that are present in earthworms.They are septal nephridia,integumentary nephridia,and pharyngeal nephridia.Septal nephridia is present on both the sides of the intersegmental septa from segment 15 to the last segment and the last segment opens into the intestine region.The integumentary nephridia are attached to the lining of the body wall from segment 3 to the last that opens on the body surface, and pharyngeal nephridia are present as three paired tufts in the 4th, 5th and 6th segments.All these three types of nephridia are basically similar in structure.Nephridia helps in the regulation of the volume and composition of body fluids.
Earthworm
Earthworms are reddish brown in colour
They mainly live in the upper layer of moist soil
The common Indian species of earthworms are Pheretima and Lumbricus
Body of earthworms is cylindrical in shape.The body is divided to form hundreds of similar short segments.
The first body segment of earthworm is termed peristomium.Mouth is present in this segment.
The alimentary canal of earthworm is straight