Question

What is contractile vacuole?

And how is it different from normal vacuole

Answer 1

Contractile vacuole, regulatory organelle, usually spherical, found in freshwater protozoa and lower metazoans, such as sponges and hydras, that collects excess fluid from the protoplasm and periodically empties it into the surrounding medium. It may also excrete nitrogenous wastes. In amoebas it changes position with the animal's movement; in most ciliates it follows a definite path through the cell; in the Euglena and other flagellates it remains stationary. The filling and emptying cycle may last from seconds to a minute, depending on the species.

There is nothing regarding the difference between a normal vacoule. Because contractile vacoule is one among the various vacoules. Another vacuole is food vacoule.

The difference between food vacoule and contractile vacoule is :
Contractile vacuole found in protists such as Amoeba and unicellular algae carries osmoregulation of the cell. It stores and excretes out the excess water of the cell.
Food vacuole stores the nutrients required for growth and development