"Paramecium and some other single-celled eukaryotes rely on a set of organelles called the contractile vacuole complex that are connected to the outside through a pore. The contractile vacuoles go through cycles of filling and expelling. As the vacuole fills up with fluid from inside the organism, the pore closes up--keeping everything inside the vacuole. When that's done, the pore opens back up. You know, for the peeing."
Journey to the Microcosmos- How Do Microorganisms Pee?
Images Originally Captured by Jam's Germs













