What do protists use to regulate water?

Protists use contractile vacuoles to regulate water and maintain osmotic balance. These vacuoles collect excess water that enters the cell and expel it through a process of contraction. This mechanism is especially important for freshwater protists, which are constantly gaining water due to the lower concentration of solutes in their environment compared to their cytoplasm. By effectively managing water levels, protists can prevent cell lysis and maintain homeostasis.