Euglena live in fresh and brackish water environments that are rich in organic compounds, such as ponds or lakes. They are also capable of surviving outside of these environments in an inert form known as a cyst, waiting for water to return.
Euglena move through their environments by using a tail-like appendage, known as a flagellum, which they wave back and forth to push through the water. They are not related to algae but are capable of getting energy both by consuming organic compounds and through photosynthesis. They have eyespots that allow them to detect and stay near sources of light.