Stentor polymorphus. Light microscope footage of several of green stentor (Stentor polymorphus), feeding while attached to plant material. This species of freshwater ciliate protozoan feeds mainly on bacteria, using its hair-like cilia to waft food particles into its oral area. Its green colour is caused by the presence of numerous individual Zoochlorella sp. algae, with which it has a symbiotic relationship. The algae photosynthesise inside the protozoan, providing it with sugars and oxygen, while deriving protection from their host. Filmed with darkfield illumination.