Nephridia of Earthworm are analogous to

The colour of the body in earthworm is brown due to the presence of

Which structure in the alimentary canal of an earthworm is lined by an internal cuticle?

Match the regions of the earthworm based on the clitellum:
$P$ - Segments $14$ to $16$
$Q$ - Segment $17$ to the last segment
$R$ - Segments $1$ to $13$
Identify the correct sequence for the Pre-clitellar region,Post-clitellar region,and Clitellar region,respectively.

The locomotory organ of an earthworm is ..........

The approximate number of earthworms found in $1$ acre of land is..........