Platyhelminthes

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Photo courtesy of Dennis Anderson.

Platyhelminthes, also known as "flatworms," have bilateral symmetry and are a simple animal. They are also triploblastic, which means they are made up of three cell layers. Third, flatworms are without a body cavity and anus. A pharyngeal opening excretes wastes and takes in food. Some larger flatworms contain body cavities.

The following table includes the division of Platyhelminthes into four classes:

Here are ten basic facts about Platyhelminthes:
1. They have three layers of cells.
2. They are bilateral in symmetry.
3. They lack organs for repiration and therefore the cells allow gases to to diffuse out in from their surroundings.
4. They use sexual and asexual reproduction.
5. They have a partial digestive system.
6. They have an excretory system.
7. Flatworms are predominantly hermaphraditic.
8. They have a muscular system.
9. Flatworms are composed of free living forms and parasites.
10. They are motile.