Home >> Science & Nature >> Animals & Science

How to Differentiate Between the Three Classes of Flatworms

The phylum Platyhelminthes, or flatworms, comprises three classes: Turbellaria, Trematoda, and Cestoda. These three groups are more commonly known as planarians, flukes, and tapeworms, respectively. As a whole, flatworms are important because they have several key traits in common with humans. They exhibit bilateral symmetry (having a left and right side), cephalization (having a distinct head region), and they are triploblastic, meaning they develop from three cell types in the embryo. Humans share all of these traits.

Things You'll Need

Magnifying glass or microscope

Instructions

- 1
  Find out the flatworm's home environment. If it is free-living, it is a planarian. If it is parasitic, it is either a fluke or a tapeworm.
- 2
  Look at the flatworm's head. If it has a mouth, it is a fluke. Flukes also have one or more suckers around the mouth. If it has no mouth, it is a tapeworm. Tapeworms have much simpler digestive tracts than flukes or planarians.
- 3
  Look at the worm's body. If it is broken up into individual segments, it is a tapeworm. In a tapeworm, each of these segments is an egg case at different developmental stages.

Animals & Science