Stentor ciliate protozoan. Differential interference contrast (DIC) light micrograph of a Stentor polymorphus ciliate protozoan preparing to eat algae (green, upper right). This freshwater protozoan feeds mainly on bacteria. It moves by beating its cilia, hair-like extensions that cover its body. The small green bodies inside the protozoan are individual Zoochlorella sp. algae, which have a symbiotic relationship with the protozoan. They photosynthesise inside the Stentor, providing it with sugars and oxygen, while deriving protection from their host. Magnification: x143 when printed at 10 centimetres wide.