The Oregon giant earthworm (''Driloleirus macelfreshi'') is one of the largest earthworms found in North America, growing to more than three feet (0.91 m) in length. First described in 1937, the species is not common. Since its discovery, specimens have been documented in only fifteen locations within Oregon's

Willamette Valley The Willamette Valley ( ) is a long valley in Oregon, in the Pacific Northwest region of the United States. The Willamette River flows the entire length of the valley and is surrounded by mountains on three sides: the Cascade Range to the east, ...

Taxonomy and description

The Oregon giant earthworm was first described by Frank Smith in 1937 from a specimen found near Salem, Oregon in 1903. The species was named in honor of its collector, F. M. McElfresh.Smith (1937) Like its cousin, the

giant Palouse earthworm The giant Palouse earthworm or Washington giant earthworm (''Driloleirus americanus'', meaning ''lily-like worm'') is a species of earthworm belonging to the genus '' Driloleirus'' inhabiting the Palouse region of Eastern Washington and North Ida ...

(''Driloleirus americanus'') of Washington, this species can grow to lengths in excess of 3 feet (0.91 m) and up to an inch (2.5 cm) in width. When handled, the worms emit a peculiar aroma that is reminiscent of

flower A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division Angiospermae). The biological function of a flower is to facilitate reproduction, usually by providing a mechani ...

s—hence their genus name ''Driloleirus'', which means "lily-like worm".Jordan (2009) The life history of this species is not well understood and is based on a very limited number of observations. They live in the deep, moist, undisturbed soils of riparian forests. They tunnel deep into the soil and are known to dig permanent burrows fifteen feet below the surface. However, during the wetter seasons, they are found closer to the soil surface feeding on the rich layers of accumulated organic material.

Distribution and habitat

The Oregon giant earthworm is

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...

to Oregon and has been found at 15 sites in the

and one additional site within the Oregon Coast Range. Like Oregon’s other indigenous worms, this species has a narrow range of tolerance for soil conditions, favoring fine textured soils rich in clay. It appears to prefer well drained soils (fine-grained, clay to silt loams) that are near subsurface water, often where the water table is reachable but the soil is not waterlogged. This species is associated with deep, little-disturbed soils in moist mixed forest of

Douglas firs The Douglas fir (''Pseudotsuga menziesii'') is an evergreen conifer species in the pine family, Pinaceae. It is native to western North America and is also known as Douglas-fir, Douglas spruce, Oregon pine, and Columbian pine. There are three va ...

, grand firs, and bigleaf maples and is also known from pure Douglas-fir woodlots and occasionally from oak-ash woods. It is apparently tolerant of the acidic soil found under coniferous forests.

Conservation status

Because this species is so elusive, being last sighted in 2008, it is very difficult to estimate populations or assess potential threats. Habitat loss and competition from introduced earthworms are thought to be two major threats. In the Willamette Valley, less than one percent of the original native grasslands remain, and conversion of land for agriculture, industry, and housing development has eliminated much of this species’ suitable habitat.

Notes

References

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External links

Oregon giant earthworm
from pacificbio.org (archived link) Animals described in 1937 Endemic fauna of Oregon Megascolecidae Taxonomy articles created by Polbot {{Annelid-stub