Organisms in phya nematodes are bilaterally symmetrical. They are also called roundworms. Round worms are covered with epidermal cells. Underneath them are muscle cells. Inside the cavity of a roundworm are intestines oviducts or testes. The body cavity of roundworms are pseudocoel which means that the fluid inside them is under high pressure. Nemotodas have a simple nervous system that is a ring of nervous tissue that goes around the pharynx and runs down the length of the body. Nemadota have no circulatory system, but have specialized cells which excrete nitrogenous wastes. Nemotadas reproduce sexually where the male injects his sperm into the female.
Hookworm (Necator Americanus)
Myers, P. 2001. "Nematoda" (On-line), Animal Diversity Web. Accessed February 28, 2011 http://animaldiversity.ummz.umich.edu/site/accounts/information/Nematoda.html.
