In earthworms,exonephric excretion occurs through:

In $Pheretima$,there are red-coloured round bodies in the $4th$,$5th$,and $6th$ segments above the alimentary canal. They are believed to be involved in:

Which of the following statements is true regarding haemoglobin?

In $Pheretima$,septa are absent between which segments?

Define the following terms:
$(i)$ Cocoon
$(ii)$ Worm casting

Select the incorrect option for the earthworm $(Pheretima)$.