Question

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

Answer 1

(a)

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.