The Nematoda phylum
Nematodes occur in nearly every habitat including as parasites in all sorts of plants and animals. Though only about 80,000 species have been found by scientists, some say that there may be as many as a million different species of Nematodes! They tend to live in groups in dense numbers. Many live in the soil and in rotting vegetables but most live in the top soil of dirt. Most Nematodes are parasites, many of which cause disease in humans and other animals.