Dugesia is a genus of flatworms containing some common representatives of the class Turbellaria. These common flatworms can be foun in freshwater habitats. Their digestion tract consists of a central tubular pharynx. Each branch consists of ceca, which delivers the nutrients to the body. This worm has a sac digestive plan, that is, it does not have a separate opening for waste excretion. (Gilbertson, 1999).