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Question -

Distinguish between the following:
(a) Prostomium and peristomium
(b) Septal nephridium and pharyngeal nephridium



Answer -

a) Prostomium andperistomium

Prostomium

Peristomium

Small, fleshy lobe, serves as a covering for the mouth and as a wedge to force open cracks in the soil wherein the earthworm crawls.

It is the crescentic aperture at the anterior end of the first segment of the earthworm comprising the mouth

┬а

b) Septal nephridiumand pharyngeal nephridium

Septal nephridium

Pharyngeal nephridium

Found at the anterior and posterior surface of septa occurring after segment 15 in earthworm

Found in three pairs in the 4th, 5th┬аand 6th┬аsegments located on either side of the alimentary canal

Excretory matter is discharged into the lumen of the alimentary canal

Excretory matter is discharged into the gut, in the pharynx or buccal cavity

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