These organisms are single-celled and elongated, ranging from 15 to 500 µm in size. They typically exhibit a green coloration due to the presence of chlorophyll pigment. Unlike typical cells, they lack a cellulose cell wall and instead possess a flexible outer membrane known as a pellicle. Additionally, they contain a contractile vacuole responsible for expelling excess water. Near the base of their flagella, there is an inward pocket known as a reservoir. Reproduction primarily occurs through asexual binary fission, where they divide longitudinally.