Light microscope differential interference contrast (DIC) footage of ciliate protozoan Paramecium sp., showing its internal structure. The nucleus, digestive vacuoles, large contractile vacuoles, and various particles can be seen. Paramecium are abundant in water and soil. They move by the rhythmic beating of many hair-like cilia, feed mainly on bacteria. These are digested within temporary digestive vacuoles which float within the cell cytoplasm. The contractile vacuoles act as osmotic regulators, controlling the flow of water across the ciliate's membrane.