
Phylum: Acoelomates, Platyhelmithes
Classes:Trematoda, Cestoda, Monogenea, Turbellaria
Flatworms, Its class is Phylum they are found in marine, fresh water and damp environments. It is a simple soft bodied in vertebrae. Their body are also ribbon like. animal. There are about 25000 known species. Like all animals flat worms do breathe oxygen they use the interstial fluids to help distribute the nutrients and oxygen because they have no respiratory or circulatory system in their body but they do have a nervous system. Flatworms produce sperm and eggs they can reproduce sexually and asexually. Many of the flatworms are parasitic. There are four types of flat worms Trematoda, Cestoda, Monogenea, and Turbellaria. A common flatworm that we know are known as tapeworms. Most parasitic flatworms feed off their host which is very dangerous for the host. It may also eat smaller life forms some even eat algae to survive.
Links
http://www.earthlife.net/inverts/platyhelminthes.html
http://www.mcwdn.org/Animals/Flatworm.html
http://en.wikipedia.org/wiki/Flatworm