Light microscope footage of Paramecium caudatum ciliates. The Paramecium at centre shows pulsation cycles of two contractile vacuoles. These act as osmotic regulators, controlling the influx of water across the ciliate's membrane by active expulsing the water out of the cell via the expulsing pores. Paramecia move by the rhythmic beating of many hair-like cilia, and feed mainly on bacteria, which are wafted to its mouth by the cilia. The bacteria are then digested within temporary digestive vacuoles, which float within the cell cytoplasm. Filmed with differential interference contrast illumination. Captured field width: 0.25 millimetres.