What are worm castings?

What is the function of nephridia?

Notochord in earthworm is .................... and nerve cord is ..................

Choose the correct pair regarding the anatomy of an earthworm:

Column-$I$	Column-$II$
$1$. Spermathecae	$a$. $6^{th}$ to $9^{th}$ segments
$2$. Typhlosole	$b$. $1^{st}$ to $3^{rd}$ segments
$3$. Buccal cavity	$c$. $26^{th}$ to $35^{th}$ segments in intestine
$4$. Pharyngeal nephridia	$d$. $4^{th}$ to $6^{th}$ segment

Locomotion in earthworm is directly facilitated by

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: