eelworm

Any of several species of nematode, named for their resemblance to miniature eels. Eelworms are either free-living or parasitic, and most are about 0.005–0.05 in. (0.1–1.5 mm) long. They are found in all parts of the world. Free-living forms inhabit salt water, freshwater, and damp soil. Parasitic forms are found in the roots of many plant species; the potato-root eelworm, for example, is a serious pest of potatoes. Some species occur in both plants and animals.