Platyhelminthes

The flatworms known as //Platyhelminthes// are a phylum of relatively simple bilaterian, unsegmented, soft-bodied invertebrate animals. Unlike other bilaterians they have no body cavity, and no specialized circulatory and respiratory organs, which restricts them to flattened shapes that allow oxygen and nutrients to pass through their bodies by diffusion. Over half of all known flatworm species are parasitic, some of which do enormous harm to humans and their livestock. Below are six of the more interesting //Platyhelminthes.// Click on a photo to link to the respective flatworm's page.