What is a contractile vacuole? State its function in Amoeba.

The contractile vacuole is a vacuole in which the excess of water from the body of the amoeba is collected. The function of the contractile vacuole in Amoeba is excretion. Ammonia is the main waste product of amoeba which dissolves in water and is excreted through the general body surface by simple process of diffusion.