Planarians

a group of invertebrates of the suborder Tri-cladida of the class Turbellaria. Planarians are quite large, reaching a length of 35 cm. They are distributed throughout the world. The worms live in freshwaters and, less frequently, in seas; in the tropics they are also found in the soil. They feed on small invertebrates. Fishes do not eat planarians because the skin contains poison glands.