Euglena

Euglenas are single-celled, flagellate eukaryotes found in both freshwater and saltwater environments. They possess two flagella located in a small reservoir at the front of the cell; one is very short and remains inside the cell, while the other is longer and used for swimming in some species. Most euglena species contain photosynthesizing chloroplasts, allowing them to harness sunlight for energy, similar to plants. However, they can also feed heterotrophically, like animals. The bright red spot on euglena, often mistaken for a photosensitive organ, actually functions as a light filter, directing sunlight to a light-sensitive structure at the base of the flagellum known as the paraflagellar body. Euglena cells are surrounded by a pellicle, a protein layer reinforced by microtubules arranged in spiraling strips around the body, providing flexibility and shape. Euglenas reproduce asexually through binary fission.