Paramecium bursaria amongst pond debris. This ciliate protozoan has a symbiotic relationship with the green alga called Zoochlorella. The algae live inside the Paramecium in its cytoplasm and provide it with food, while the Paramecium provides the alga with movement and protection. Paramecium bursaria has a wide oral groove, two contractile vacuoles, and a single micronucleus as well as a single macronucleus. It is the only species of Paramecium that forms symbiotic relationships with algae, and it is often used in biology classrooms both as an example of a protozoan and as an example of symbiosis