Lumbriculus variegatus, also known as the blackworm or California blackworm, is a species of worm inhabiting North America and Europe. It lives in shallow-water marshes, ponds, and swamps, feeding on microorganisms and organic material. An adult individual has approximately 150 to 250 segments, each of which has the ability to regenerate into a new individual when separated from the rest of the animal. In most populations, this is the primary mode of reproduction, and sexually mature individuals are exceedingly rare; in large areas (including Asia, most of North America and the greater part of Europe) sexually mature individuals have never been found.