n.
Any of more than 1,800 species of terrestrial worm s, particularly members of the genus Lumbricus (class Oligochaeta of the annelid order).
Earthworms exist in all soils of the world that have sufficient moisture and organic content. The most common U.S. species, L. terrestris, grows to about 10 in. (25 cm), but an Australian species can grow as long as 11 ft (3.3 m). The segmented body is tapered at both ends. Earthworms eat decaying organisms and, in the process, ingest soil, sand, and pebbles, which aerates the soil, promotes drainage, and improves the soil's nutrient content for plants. Earthworms are eaten by many animals.
Earthworm ( Lumbricus terrestris ).
John Markham