Nematoda is a phyla that has about 80,000 known species. Some scientists believe that there is an estimate of as many as a million different species. The round worm, perhaps the most commonly known species of the Nematoda phyla, have very developed Nervous systems. It is made up of a nerve ring that is made of four ganglia. From the ganglia, there are six nerves that run through their body. They are connected to different parts of the gut and some reproductive organs. There are also six more nerves that run through the body connected to the mouth.