Here's how it works:

* Osmosis: Amoebas live in freshwater environments. Due to the difference in solute concentration between the amoeba's cytoplasm and the surrounding water, water constantly flows into the amoeba by osmosis.

* Contractile Vacuole Formation: The contractile vacuole, a small, clear sac within the cytoplasm, collects the excess water.

* Contraction and Expulsion: The contractile vacuole then contracts, squeezing the water out of the amoeba through a small opening called a pore.

This process helps maintain the amoeba's internal water balance and prevents it from bursting due to excessive water intake.