Euglena rostrifera (Protozoan) Videos
Some species that don't have a rigid cellulose wall have a flexible pellicle (envelope) that allows them to change their shapes. Food is absorbed directly through the cell surface or produced by photosynthesis; then it is stored as a complex carbohydrate. Euglena reproduce asexually, by longitudinal cell division; they are not know to reproduce sexually. Several species produce resting cysts that can withstand drying. Euglena live in fresh and brackish water habitats rich in organic matter. Some species develop tremendous populations as green or red "blooms" in ponds or lakes. Several colorless species are used to study cell growth and metabolism at high temperatures.