A flatworm is any member of the phylum Platyhelminthes, which is a group of flattened invertebrates that have soft bodies. There are different species of flatworm, but 80 percent of them are parasitic. This means that most flatworms live in another organism to obtain nourishment from it.
Flatworms do not have specialized circulatory, respiratory and skeletal systems. Moreover, the bodies of flatworms are not segmented, and they are bilaterally symmetrical. Flatworms also have mesenchyme, or spongy connective tissues that compose the parenchyma and fill the gaps between organs. Lastly, these organisms are hermaphroditic, which means they have functional male and female reproductive organs.