Excretion in amoeba

The amoeba lives in fresh water bodies like lakes, slow moving streams and ponds. Amoeba excretes excess carbon dioxide, water and ammonia. Ammonia is excreted across the cell membrane although it can also be excreted by the contractile vacuole when it dissolves in water.

Carbon dioxide is excreted by diffusing across the cell membrane. Osmoregulation is achieved by the contractile vacuole. The excess water collects in the contractile vacuole and then it migrates and fuses with the cell membrane hence releasing the water to the outside.

Excretion in insects

Insects excrete carbon dioxide and uric acid crystals. Uric acid being a nitrogenous waste product is excreted by the malpighian tubules which are found between the junctions of the mid gut projecting into the blood filled cavity.

Excretion in annelids

Excretion in the annelids such as the earthworms is carried out by the niphridia which are found in each segment. They release the waste products through the opening s found on the body surface

Excretion in birds

Birds excrete carbon dioxide and uric acid. They use the lungs to excrete carbon dioxide and the kidney to excrete uric acid.