The Anus
Platypuses have a cloaca, which is used for both excretion and reproduction.
Kidneys
skin
The kidneys are the principal organ.
heart Internal organ maybe, but the largest organ is your skin.
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.
The cerebellum in the brain.
The principal nitrogen excretion product of metabolism in humans is urea. It is produced in the liver as a way to remove excess nitrogen from the body, which is generated during protein metabolism. Urea is then excreted by the kidneys in the urine.
kidney
Kidneys
The primary organ of excretion is the kidney. Kidneys filter waste products from the blood to produce urine, which is then excreted from the body.