Interphako contrast light micrograph of a group of Euglena gracilis protozoan green algae. Euglena sp. protozoa are commonly found in puddles in such large numbers that they turn the water green. In water poor in organic matter, E. gracilis obtains its nourishment through photosynthesis using its light-sensitive chlorophyll pigments. However, in water rich in organic substances it will lose its pigmentation and feed in an animal-like manner, even if light is present. Euglenoids move by means of flagella, whip-like structures at the ends of their bodies. Magnification: x125 at 35 millimetre size.