Nematodes, or Nematoda are much like the Platyhelminthes in the sense that they have only one main organ, the gut. This also means that the Nematodes use diffusion to transport nutrients throughout their body. Because they use diffusion like the Platyhelminthes, they are able to have such a small form factor. The only major difference between both the Nematoda Phylum, and the Platyhelminthes is that the Nematoda phylum has a large amount of liquid within its body that also allows nutrients to flow through their systems.