The Anus
the principal nitrogen-excretion product of metabolism
Platypuses have a cloaca, which is used for both excretion and reproduction.
kidney
Kidneys
skin
The Liver.
I think for me the process of excretion with the process of defecation is by the process of excretion with the process of defecation. Therefore the defecation is the process of excretion by the process of defecation. Some says excretion is the process with the defecation process. That's why the organ contrast the process of excretion with the process of defecation.
The kidneys are the principal organ.
The skin is considered an organ of excretion because it sweats, getting rid of toxins and certain mineral salts.
Worms use their skins for excretion mostly.
Kidneys
kidney