Euglena protozoan. Light microscopy footage of the flagellate protozoan Euglena spirogyra moving in water. This freshwater single_celled organism can either obtain energy from sunlight, via photosynthesis, or by absorbing chemicals from its surroundings. Like many protozoa, Euglena is an active swimmer, moving by beating an extension of its cell membrane known as a flagellum. This footage was recorded with differential interference contrast DIC microscopy techniques.