A "flagellate protozoan" is a single-celled microorganism that typically possesses one or more whip-like structures called flagella, which they use for movement. A common flagellate protozoan is the Trypanosoma, which is responsible for causing sleeping sickness in humans. Other synonyms for flagellate protozoans include motile protozoans, whip-like protozoans, and flagellate unicellular organisms. Examples of flagellate protozoans include Euglena, Leishmania, and Giardia, which are responsible for causing various diseases in humans and animals. Flagellate protozoans are important components of aquatic ecosystems, where they contribute to the food chain and help regulate the population of other microorganisms.