Platypuses have a cloaca, which is used for both excretion and reproduction.
Kidneys
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 Anus
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.
The kidney is the main organ, that is responsible for the excretion of waste products. Other organs of excretion are your liver, lungs and skin.
lung
Amniotic sac
Amniotic sac