Fresh water ciliate protozoan. Scanning electron micrograph (SEM) of a cilliate protozoan (unicellular animal) found in a fish pond. The ciliates are so named because of the hair-like cilia surrounding their bodies which are used for locomotion and sweeping in food. Their diet consists mainly of bacteria and other food particles, which are digested in a food vacuole. They live in water and are typically invisible to the naked eye, although the largest ciliate reaches a length of 2 millimetres. Magnification: x4000 when printed at 10 centimetres wide