Cytoplasmic movements in Euglena gracilis protist, light micrograph. Euglenoids are a variety of microscopic green algae with a locomotor organ known as a flagellum. They are frequently found in nutrient-rich aquatic environments, mainly freshwater. Able to photosynthesise, thanks to the presence of chloroplasts, they are autotrophic for carbon. Under certain conditions, they can also feed on organic matter, making them highly original organisms. Euglenoid cells are typically elongated or spindle-shaped, sometimes round, with a long flagellum located posteriorly, but also a very short, inconspicuous flagellum confined to a small cavity: the reservoir. A bright red stigma, a rudimentary light sensor, is often located near the base of the main flagellum. Euglenoids reproduce by simple binary division, i.e. asexual reproduction. Magnification: x700 when printed at 10 centimetres wide.