A euglena is a unicellular organisms with flagella. A euglena is a flagellate protist. It is the best known and most widely studied member of the class Euglenoidea. Euglenoidea is a diverse group of protists that contain fifty-four genera and approximately 800 species. The euglena is oblong in shape. Euglena contain chlorophyll. This is the same green pigment that is housed in the thylakoids of plant cells. Chlorophyll captures sunlight energy during photosynthesis. Photosynthesis is the process that uses sunlight energy in order to convert carbon dioxide and water into glucose (a sugar) and oxygen. Thus, euglena can act as a producer and make their own food (energy) via photosynthesis. However, euglena can also act like a consumer. When sunlight is lacking, the euglena feed on tiny plant-like substances (such as algae) or amoeba and paramecium.