Ncert Exercises & Solutions

5. Distinguish between the followings

(a) Prostomium and peristomium

(b) Septal nephridium and pharyngeal nephridiu

Prostomium

Peristomium

Prostomium is a small fleshy lobe, which overhangs the mouth of an earthworm. It helps the organism push into the soil and is sensory in function.

The first body segment in the
earthworm is called the
peristomium. It surrounds the
mouth opening.

( b )

Septal nephridium

Pharyngeal nephridium

They are present on both sides of
intersegmental septa behind the 15th segment. They open into the intestines.

They are present as three paired
tufts in the fourth, fifth, and sixth
segments.