Flatworms are bilaterally symmetrical. Their body has 3 layers of tissues with organelles and organs. They do not have an internal cavity in their body. They have a mouth but no anus. They have Protonephridial excretory organs instead of an anus. They have a nervous system of longitudinal fibers. They have a flattened shape( hence the name). They are hermaphrodites and perform sexual reproduction. They feed on animals and smaller life forms.