PLATYHELMINTHES
- This phylum is composed of 12,00 species
- Species in this phylum are also known as flatworms
- These species are soft-bodied and simple invertebrates that lack a body cavity
- The three organisms are: Bedford's Flatworm, Tapeworm, and Tremadota
Bedford's flatworm
Bedford's Flatworm lacks any definite respiratory organs. This means that the flatworm's body is shaped so that oxygen can enter and carbon dioxide can leave through all parts of the body by simple diffusion. It has a space between the skin and the gut that is filled with mesenchyme which is a connective tissue reinforced with collagen that allows enough room for oxygen and carbon dioxide to pass through. Using diffusion to breathe leaves flatworms vulnerable to dehydration so they live in either a fresh or salt water environment.
tapeworm
Like the flatworm, tapeworms lack any type of respiratory organs. They use diffusion as well to move oxygen into the gut in the body cavity and to move carbon dioxide out. However, tapeworms have little to no mesenchyme in between the skin and the gut as their long and thin body shape leaves little room. Also, in order to prevent dehydration when using a process that makes them vulnerable like diffusion, tapeworms rely on the fluids found in intestinal tracts of other organisms while flatworms rely on water.
Trematoda
Trematoda, also called "fluke" are similar to flatworms in that they lack respiratory organs. They also have mesenchyme in between the skin and the gut allowing diffusion to occur so that oxygen can enter the gut and carbon dioxide can leave it. Fluke are unique, however, in that there parasitic nature allows them to rely on water when outside a host or the fluids of a host's intestines to stay hydrated during the vulnerable process of diffusion.