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Lumbricus terrestris is a large, reddish worm species thought to be native to Western Europe, now widely distributed around the world (along with several other Lumbricidae). In some areas where it is an introduced species, some people consider it to be a significant pest for out-competing native worms.
Through much of Europe, it is the largest naturally occurring species of earthworm, typically reaching 20 to 25 cm in length when extended.
Although this is not the most abundant earthworm, even in its native range, it is a very conspicuous and familiar earthworm species in garden and agricultural soils of the temperate zone, and is frequently seen on the surface, unlike most other earthworms. It is also used as the example earthworm for millions of biology students around the world, even in areas where the species does not exist. However, 'earthworm' can be a source of confusion since, in most of the world, other species are more typical. For example, through much of the unirrigated temperate areas of the world, the "common earthworm" is actually Aporrectodea (= Allolobophora) trapezoides, which in those areas is a similar size and dark colour to L. terrestris.
The worm has a hydrostatic skeleton and moves by longitudinal and circular muscular contractions. Setae – tiny hair-like projections – provide leverage against the surrounding soil, using slime liquid. Surface movements on moist, flat terrain were reported at a speed of 20 m/h and, based on measurements of the length of the trail, nocturnal activity away from the burrow was estimated at up to 19 m during a single surface foray. Such movement is apparent during and after heavy rainfall and usually happens when people become aware of relatively large numbers of earthworms in, for example, urban ecosystems. This form of activity is often considered a way to escape floods and waterlogged burrows. However, this cannot be the case since L. terrestris, like other earthworms, can live in oxygenated water for long periods of time, stretching to weeks. Under less severe environmental conditions where air temperature and moisture are sufficient, the worm often moves around on the surface. This may be driven by resource availability or the desire to avoid mating with close relatives.
Its activity is limited by temperature and humidity. High soil and night air temperatures inhibit activity, as do low night moisture and dry soil. During such times, particularly in the summer, the worms will retreat to the deepest parts of their burrows. Winter temperatures can also reduce activity, while activity in maritime climates can continue through winter.
Lumbricus terrestris can strongly influence soil fungi, creating distinctive micro-habitats called middens, which strongly affect the spatial distribution of plant litter and litter-dwelling animals on the soil surface. In the soil system, L. terrestris worm casts have a relationship with plants which can be seen in such scenarios as plant propagation from seed or clone. Worm casts initiate root development, root biomass, and in effect, increase root percentage as opposed to the soil and soil systems without worm casts.
In parts of Europe, notably the Atlantic fringe of northwestern Europe, it is now locally endangered due to predation by the New Zealand flatworm ( Arthurdendyus triangulatus) and the Australian flatworm ( Australoplana sanguinea), two predatory Platyhelminthes accidentally introduced from New Zealand and Australia. These predators are very efficient earthworm eaters, being able to survive for lengthy periods with no food, so still persist even when their prey has dropped to unsustainably low populations. In some areas, this is having a seriously adverse effect on the soil structure and quality. The soil aeration and organic material mixing previously done by the earthworms has ceased in some areas.
While they generally feed on plant material, they have been observed feeding on dead insects, soil micro-organisms, and feces.
Sperm is stored for as long as 8 months, and mated individuals produce cocoons for up to 12 months after the mating. Fertilization takes place in the cocoon and the cocoon is deposited in a small chamber in the soil adjacent to the parental burrow. After a few weeks, young worms emerge and begin to feed in the soil. In the early juvenile phase, the worms do not develop the vertical burrows typical of adults. Adulthood is likely to require a minimum of one year of development, with reproductive maturity reached in the second year. The natural lifespan of L. terrestris is unknown, though individuals have lived for six years in captivity.
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