Excretion in Paramecia As mentioned in Chapter 5, Section 5.2, paramecia are unicellular protozoa which feed on micro-organisms such as bacteria. Metabolic wastes are expelled from a paramecium through exocytosis. Digested material from a food vacuole moves through the cytoplasm, the Vacuole shrinks and travels to the anal pore where ruptures expelling the waste contents into the environment on Excess water is removed through osmoregulation and this is carried ou by a pair of contractile vacuoles into the surrounding. Figure 6.1 (b) shows a pair of contractile vacuoles in Paramecium aurelia.