Overview of the Phylum:
The phylum Platyhelminthes, or flatworms, are a phylum of relatively simple bilaterian, unsegmented, soft-bodied invertebrates. Unlike other bilaterians, they have no body cavity and have no specialized cardiovascular and respiratory organs, which restricts them to having flattened shapes that allow oxygen and nutrients to pass through their bodies by diffusion. There are about 29,000 species of this phylum. Platyhelminthes are divided into turbellaria which are made up of mostly non-parastic animals and three parasitic groups which are Cestoda, Trematoda, and Monogenea. |
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