The phylum Euglenozoa is placed in the kingdom Protozoa (Cavalier-Smith, 2016), and only the class Euglenophyceae in the phylum Euglenozoa acquired green algal chloroplasts—a process called symbiogenesis. Because of the symbiotic origin, the chloroplast is surrounded by an extra membrane. They have both chlorophyll a and b, making the organisms grass-green in color. They also have betacarotene, diadinoxanthin, and as in Euglena sanguinea (see Fig. 6.4), the red pigment astaxanthin. All euglenoids can use sunlight as an energy source, but some are also facultative heterotrophs, obtaining energy and nutrients by consuming other organisms or organic compounds in the water. The morphology of the chloroplasts varies widely, from discoid to ribbons, and the number per cell can range from a couple to several hundreds. All these features are used to identify the organism. Most of the euglenoids are highly motile, with two flagella that originate in a subapical groove. Most genera have one long flagellum that emerges from the groove and provides helical movement of the cells. The other flagellum is typically confined to the groove. All also have a red-orange eyespot (b-carotene) and a strong phototactic response to light.