Question

Distinguish between the followings

(a) Prostomium and peristomium

(b) Septal nephridium and pharyngeal nephridium

Answer 1

Prostomium :

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.

Peristomium :

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

Septal nephridium :

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

Pharyngeal nephridium :

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