The Phylum Platyhelminthes, also known as flatworms, is a group of invertebrates that are characterized by their flattened, soft bodies. Some common synonyms for this phylum include flatworms, platyhelminths, and planarians. Flatworms can be found in a variety of habitats, from freshwater ponds to marine environments. They are known for their ability to regenerate, with some species capable of regrowing entire body parts. Some species of flatworms are parasitic, and can cause serious illnesses in humans and animals. Despite their small size, flatworms play an important role in the ecosystem as decomposers and food sources for larger animals.