There are three types of flatworms:
What is a Planarian?
Planarians are an example of free-living flatworm. Planarians feed mostly on small organisms or organisms of dead bodies. Most live under rocks, on plant materials, or in freshwater. They reproduce asexually and sexually. When they reproduce asexually the seperate into two. When planarians reproduce sexually they produce eggs and sperm.
What is a Fluke?
All flukes are parasites with complex life cycles and require more than one host. Most flukes produce sexually. Of many diseases caused by flukes, the most widespread one affecting humans is Schistosomiasis. More than 200 million people, mostly in developng countries are infected with blood flukes.Blood flukes are one of the worst flukes; often causing humans or other animals to either die, or become very weak.
It is estimated that one million people die each year becuase of flukes. Other flukes affect lungs, livers, eyes, and other organs. Blood flukes are another example of a fluke. Flukes reproduse sexually, similar to how free-living flatworms reproduce.
What is a Tapeworm?
Tapeworms are parasites. The head attaches to intestials walls of humans and animals. Dogs, cats, humans, and other animals are hosts for tapeworms. The longest tapeworm recorded has been over 18 meters long! Tapeworms reproduce either asexually or sexually.