The brown color of the earthworm's body is due to the presence of . . . . . . .

The nephridiopore is the opening of $............$.

Chloragogen cells are involved in

In $Pheretima$,there are red-colored round bodies present above the alimentary canal in the $4^{th}$,$5^{th}$,and $6^{th}$ segments. It is believed that they are involved in:

In an earthworm,from which segment does the typhlosole begin?

What is the function of the typhlosole in an earthworm?