Trophic mutualism often occurs between an autotroph and a heterotroph. Thus, "D. acuminata" is a mixotroph, primarily a heterotroph, but autotroph once it acquires plastids. "S. flexneri" is a heterotroph. Chilomonas is a protozoa (heterotroph). A marine heterotroph, it is found in much of the world. These nutrients are made available for uptake by heterotroph bacteria and phytoplankton alike. "Reticulomyxa" is a heterotroph that can feed on prey of a range of sizes. If the heterotroph uses chemical energy, it is a chemoheterotroph (e.g., humans and mushrooms).