Differential interference contrast (DIC) light micrograph of Euglena sp. Euglena is a member of the euglenids, an abundant and well-studied group of marine and freshwater protists. Most species of Euglena have photosynthesizing chloroplasts within the body of the cell. The red spot to the right is a light sensitive eye-spot. Magnification: x575 when printed at 10 centimetres wide at its longest edge.