Earthworm

Earthworm is the common reference for the larger members of the Oligochaeta (which is either a class or subclass depending on the author) in the phylum Annelida. In classical systems they were placed in the order Opisthopora, on the basis of the male pores opening to the outside of body posterior to the female pores, even though the male segments are anterior to the female. Cladistic studies have supported placing them instead in the Haplotaxida, which also includes the family Haplotaxidae. Folk names for earthworm include "dew-worm"?"night crawler" and "angleworm."

Locomotion and importance to soil

Earthworms travel underground by the means of waves of muscular contractions which alternately shorten and lengthen the body. The shortened part is anchored to the surrounding soil by tiny claw-like bristles (setae) set along its segmented length. The whole process is aided by the secretion of a slimy lubricating mucous. In more compacted soils the earthworm actually eats its way through the soil, cutting a passage with its muscular pharynx and dragging the rest of the body along. The ingested soil is ground up, digested, and the waste deposited behind the worm. This process aerates and mixes the soil, and is often considered greatly helpful by gardeners and farmers. In addition, many earthworms will come to the surface and graze on the higher concentrations of organic matter there, mixing it with the mineral soil. Because a high level of organic matter is associated with soil fertility, an abundance of earthworms is a happy sight for the organic gardener. In fact as long ago as 1881 Charles Darwin wrote:

Related Topics:
Setae - Organic gardener - Charles Darwin

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"It may be doubted whether there are any other animals which have played so important a part in the history of the world, as have these lowly creatures"

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:(The Formation Of Vegetable Mould Through The Action Of Worms, Charles Darwin)

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Indeed, it is probably not much of an exaggeration to state that the humble earthworm is one of the most vital living creatures on the planet, for its actions are essential for the creation and vitality of soil, upon which almost all land plants and animals depend.

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