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Earthworms: Oligochaeta

Conservation Status

Seven species of earthworms are listed by the World Conservation Union (IUCN). The Australian Lake Pedder earthworm is listed as Extinct, or no longer living. Phallodrilus macmasterae from Bermuda is listed as Critically Endangered, or facing an extremely high risk of extinction in the wild. Three of the four species considered Vulnerable live in the United States. Vulnerable means the species are facing a high risk of extinction in the wild. These include the American giant Palouse earthworm from Oregon, the Washington giant earthworm from Washington state, and Komarekiona eatoni that lives in the Midwest. The fourth species is the Gippsland giant worm of Australia. It is the only species that is clearly protected.


The famous scientist Charles Darwin (1812-1882) spent 40 years observing and studying the behavior of earthworms, mostly in his garden. He was the first to see their role in making soil more fertile. He estimated that in a single acre every year the worms could haul up 7 to 18 tons of soil to the surface as body waste, or castings. Darwin's last book, The Formation of Vegetable Mould through the Action of Worms with Observations on Their Habits, was published in 1881, just six months before his death.

Another American species from Louisiana, Lutrodrilus multivesiculatus, is listed as Lower Risk, or at risk of becoming threatened with extinction in the future. These and other earthworms are threatened by loss of habitat and by the fact that many live only in a few places. For example, the grassland habitats of many species have been converted into farmland.

Additional topics

Animal Life ResourceMollusks, Crustaceans, and Related SpeciesEarthworms: Oligochaeta - Physical Characteristics, Behavior And Reproduction, Conservation Status, River Worm (diplocardia Riparia): Species Accounts - GEOGRAPHIC RANGE, HABITAT, DIET, EARTHWORMS AND PEOPLE