Euglena are small organisms in the Protist Kingdom. Euglena gracilis is just one of many species of Euglena. They do not have common names like birds or trees, so we have to refer to them by their scientific name.
Euglena are interesting because they are a sort of combination of plant and animal. They can make their own food like a plant, but they can also eat other things, like an animal. They can also swim and move. Scientists argued for years about which Kingdom to put them in, Animal or Plant? Right now they are in neither; most scientists put them in the Protist Kingdom with other microscopic organisms, such as amoeba and paramecium.
Euglena gracilis has a long hair-like thing that stretches from its body (see top picture). You need a very powerful microscope to see it. This is called a flagellum, and the euglena uses it to swim. It also has a red eyespot. Euglena gracilis uses its eyespot to locate light. Without light, it cannot use its chloroplasts to make itself food.
