The way that you will easily deduce which one it is is that you'll see the mouth first instead of the anus because of the different ways of development.
Answer and Explanation:
Platyhelminthes are mostly worm like organisms that are dorsoventrally flattened, meaning they look like a leaf and this is why they are coined names like the Tapeworm, Flatworm, Fluke and Planarian.
Most Platyhelminthes are parasites on other animals but only the Turbellarians are mostly non-parasitic. A few species are commensalists, or mutualists living with other larger organism.
They are classified into:
- Class Turbellaria
- Class Monogenea
- Class Trematoda
- Class Cestoda