Earthworms have tube-shaped bodies that are divided into rings. Worms are important for healthy soil. Their tunnels let air and water pass through the soil. Their waste has nutrients that plants need. The common earthworm is seen more than other worms because it comes aboveground to feed and mate.
- “Lumbricus terrestris.” Wikipedia, the Free Encyclopedia. Available from: http://en.wikipedia.org/wiki/Lumbricus_terrestris
- “Earthworm.” Wikipedia, the Free Encyclopedia. Available from: http://en.wikipedia.org/wiki/Earthworm
- “Lumbricidae.” Wikipedia, the Free Encyclopedia. Available from: http://en.wikipedia.org/wiki/Lumbricidae
- “Lumbricus terrestris”. Encyclopedia of Life, available from: http://www.eol.org/pages/3126801/details
Like all earthworms, L. terrestris is a hermaphrodite. It needs another earthworm to mate with and produce fertilised cocoons - it is obligatory biparental. It mates on the soil surface at night. The cocoons - hardened shells covering the egg - of L. terrestris are 4.4–7.3mm long and 3.9–5.7mm in diameter. When the young earthworm hatches it is 25mm long. L. terrestris reaches sexual maturity in about 52 weeks and they can live for up to 10 years.
Evolution and Systematics
Skin of earthworms repels soil adhesion with a thin water film, created by electro-osmotic flow.
"When a soil animal is in contact with soil, a microscopic Electro-osmotic system is formed between the stimulated body parts and the other parts nearby. As a result, water in the adjacent soil moves to the contact zones by the action of potential difference, the water film at the contact interfaces become thicker, so that the soil adhesion to the body surfaces would be reduced through lubrication. Although the amplitude of the action potential of soil animals is small, a microscopic Electro-osmostic system can be formed because the distance between the positive pole and the negative pole is very short. The zone of negative polarity produced by stimulation from the contacting soil is on the same surface as the resting body part near to stimulating zone." (Collins 2004:220)
Learn more about this functional adaptation.
- Collins, M. 2004. Design and nature II: comparing design in nature with science and engineering. Southampton: WIT.
Smaller earthworms exert more force relative to body mass because of the scaling limitations governing hydrostatic structures, thus allowing them to burrow more efficiently.
"From the work of Quillin (2000), we have some information on the forces that earthworms can exert against the walls of their burrows. The worms push hard, with radial forces running about seven times the anchoring forces involved in crawling in preexisting burrows or in resisting extraction by a robin. We noted that if membrane thickness remains constant, tolerable pressure (still assuming constant breaking stress) will vary inversely with radius. Pressure, of course, is force divided by area, and thus is proportional to force divided by radius and cylinder length. So outward force per unit body length should be independent of size or, put in the usual terms, it should scale with body mass to the zero power--F [is proportional to] Mb0.4. If, by contrast, membrane thickness scales with radius, then tolerable pressure remains constant. That implies that outward force should vary directly with radius or with body mass to the one-third--F [is proportional to] Mb0.33.
"So what does happen? For earthworms ranging from 0.01 to 8 grams, Quillin found that F [is proportional to] Mb0.4, reasonably close to the assumptions of a thickness proportional to radius and constant material strength. The bigger is the more forceful, but more closely proportional to diameter than to mass, so relative to mass, big worms are wimps. Earthworm hatchlings can push at a monumental 500 times their weight; large adults can push at (only) a still impressive ten times their weight." (Vogel 2003:411)
Learn more about this functional adaptation.
- Steven Vogel. 2003. Comparative Biomechanics: Life's Physical World. Princeton: Princeton University Press. 580 p.
- Quillin, KJ. 2000. Ontogenetic scaling of burrowing forces in the earthworm, Lumbricus terrestris. Journal of Experimental Biology. 203: 2757-2770.
Organisms, such as the common earthworm, move large volumes of matter through narrow spaces via flexible cylindrical structures.
"Flexible cylinders make body skeletons which have enormous advantages when it comes to moving around: a considerable volume of body can be passed through a small space -- hence the earthworm burrowing through the ground, or the snake slithering through tiny chinks in the rock. As a hollow tube, the cylinder can be used to conduct liquids in or out of small spaces. The mosquito sucks up blood through its cylindrical mouthparts. The elephant's trunk acts as a two-way conduit that can suck water in and blow it out with the force of a garden hose. Provided the constructive material of a cylinder is flexible enough, the cylinder can be bent round corners, or curled up tightly like a butterfly's proboscis which curls into a spiral when not in use." (Foy and Oxford Scientific Films 1982:21)
Learn more about this functional adaptation.
- Foy, Sally; Oxford Scientific Films. 1982. The Grand Design: Form and Colour in Animals. Lingfield, Surrey, U.K.: BLA Publishing Limited for J.M.Dent & Sons Ltd, Aldine House, London. 238 p.
Molecular Biology and Genetics
Statistics of barcoding coverage: Lumbricus terrestris
Public Records: 167
Specimens with Barcodes: 305
Species With Barcodes: 1
Barcode data: Lumbricus terrestris
There are 154 barcode sequences available from BOLD and GenBank. Below is a sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species. See the BOLD taxonomy browser for more complete information about this specimen and other sequences.
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Lumbricus terrestris is a large, reddish worm species native to Europe, but now also widely distributed elsewhere around the world (along with several other lumbricids) due to human introductions. In some areas where it has been introduced, some people consider it to be a serious pest species since it is outcompeting native worms.
Through much of Europe, it is the largest naturally occurring species of earthworm, typically reaching 20 - 25 cm in length when extended (though in parts of southern Europe, the native species are much larger). In September 2012, a specimen was found in SW China measuring roughly 50 cm in length. It has an unusual habit of copulating on the surface at night, which makes it more visible than most other earthworms.
Because it is widely known, Lumbricus terrestris goes under a variety of common names. In Britain, it is primarily called the common earthworm or lob worm (though that name is also applied to a marine polychaete). In North America, the term nightcrawler (or vitalis) is also used. In Canada, it is also called the dew worm, or "Grandaddy Earthworm". In the rest of the world, most references are just to the scientific name, though with occasional reference to the above names.
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 color to L. terrestris.
L. terrestris is an anecic worm. That is, it forms temporary deep burrows and comes to the surface to feed, as opposed to burrowing through the soil for its food as most other earthworms do. An unusual habit of this species is to pull leaves into the mouth of its burrow where they partially decay before being eaten. While they generally feed on plant material, they have been observed feeding on dead insects and feces.
The potential life span of L. terrestris is unknown, though it has lived up to the age of six years in captivity. The most widely accepted approximation is around four to eight years in the wild. The world record is 69 years according to the National zoo located in Washington D.C.
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 flatworms 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.
As an invasive species in North America
L. terrestris is considered invasive in the north central United States. It does not do well in tilled fields because of a lack of nutrients, pesticide exposure, and physical injuries from farm equipment. The species, however, thrives in fence rows and woodlots and can lead to reductions in native herbaceous and tree regrowth.