Microscope footage of Bursaria truncatella, a large ciliate protozoan which feeds on Paramecium, another protozoan. Ciliate protozoa are single-celled organisms found in water. They feed on other cells and decaying organic matter, which they filter in their primitive mouth, known as a buccal cavity. They move by the rhythmic beating of many hair-like cilia. Bursaria has a very large buccal cavity which allows it to ingest large particles, and it is found world-wide in freshwater and marine habitats.