Phylum Nematoda ("thread form")
Description
Phylum Nematoda, or "the roundworms", possess round, tubular bodies that are bilaterally symmetrical. They have only lengthwise muscles, they have an alimentary canal, and both a mouth and an anus. They are covered with tough cuticles and are are pseudocoelomates. They perform ecdysis, or molting. their reproduction is sexual, with internal fertilization. They are very important decomposers in the environment. They live in water or soil, or they are parasitic. some examples of the parasites are Hookworms, Trichinella, Ascarids, Pinworms and Filarial worms.