Into which classes are platyhelminthes divided? How are these classes characterized and what are some representative beings of each of them?
Platyhelminthes are divided into three classes: turbellarians (or Turbellaria),trematodes (or Trematoda) and cestodes (or Cestoda). Turbellarians are free-living platyhelminthes and their main representative is the planaria (Dugesia tigrina). Trematodes are parasites, they live inside a host and the schistosome (Schistosoma mansoni) that causes schistosomiasis is an example. Cestodes are parasites too, they do not have digestive tubes and their cells are nourished by absorption of nutrients from the host; their most popular representative are the beef and pork taenias (Taenia saginata and Taenia solium) that parasite humans.
