Contractile vacoule are formed when A food particle is engulfed. their size depends on the size of food particle. They are not predefined. Other vacoules are predefined and exist, whether the food...
I know of only three types:
central vacuole - helps maintain plants' shape and structure by storing water (hypotonic).
contractile vacuole - pumps water out of protist cells to maintain a suitable...
a contractile vacuole is an organelle from a protist cell. it forces water out of the pores to reduce osmotic pressure and prevents the cell from bursting.