Photoreceptors of earthworm occur on

In which segments of the earthworm is the clitellum located?

Identify the correct option to distinguish between the dorsal and ventral surfaces of an earthworm.
Ventral surface $\quad\quad\quad$ Dorsal surface

$A$ characteristic feature of the earthworm,$Pheretima$,is that:

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:

Through which of the following does an earthworm respire?