Nematode

The nematodes, also called roundworms or eelworms, constitute the phylum Nematoda. The cited article says species in the phylum inhabit a broad range of environments, that most species are free-living, feeding on microorganisms, but many are parasitic, that parasitic worms called helminths are the cause of soil-transmitted helminthiases, and that nematodes are classified along with arthropods, tardigrades and other moulting animals in the clade Ecdysozoa. Unlike the flatworms, nematodes have a tubular digestive system with openings at both ends. Pests and diseases recorded in the atlas as caused by a nematode are grouped under this concept.