Common earthworm

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Common earthworm
Lumbricus terrestris (26559560801) .jpg

Common earthworm ( Lumbricus terrestris )

Systematics
Trunk : Annelids (Annelida)
Class : Belt worms (Clitellata)
Order : Little bristle (Oligochaeta)
Family : Earthworms (Lumbricidae)
Genre : Lumbricus
Type : Common earthworm
Scientific name
Lumbricus terrestris
Linnaeus , 1758

The common earthworm ( Lumbricus terrestris ), also called thawworm or eelworm , is the best known and one of the most common and largest earthworm species in Europe.

features

The common earthworm is elongated, cylindrical with a pointed front and a flattened, blunt rear end. Under the slightly iridescent cuticle it is reddish to brownish in color, with the back in the front half being distinctly darker to brown-purple and becoming lighter towards the rear. The back vessel can shine through in the middle of the back. In sexually mature animals, a lighter colored and thickened belt (clitellum) can be seen in the front third of the body from February to August .

The species reaches a body length of 9 to 30 or even 35 centimeters when sexually mature. Since the worm can form new segments in a segment formation zone near the rear end, the body size also depends on the age of the individual. It is one of the largest earthworm species in Europe, but cannot be reliably differentiated from a number of related species on the basis of color and size features alone.

Its body is divided into up to 180, usually 135 to 150 segments, the number of which increases with age and which are formed near the rear end. The mouth opening is on the ventral side of the head flap that divides the first segment of the back (tanylobes prostomium). In each segment there are four pairs of bristles (chaetae) - two on the belly side and one on each flank. From the seventh or eighth segment, there are small pores in the back in the furrows behind the segments, but these are only visible when the animals are stretched. The openings of the seed pockets (Receptacula seminis) are between the 9th and 10th and between the 10th and 11th segment. The small inconspicuous female genital openings are on the 14th segment, the larger male on the 15th segment - in sexually mature animals, they are bordered by lip-shaped bulges, from the outer edge of which there is a channel that serves to transport semen (seminal groove) to the clitellum (belt) extends. This extends over the segments 32 to 37 and is saddle-shaped with bulges on the abdomen (puberty ridges) on both sides. At the end of the body (the pygidium ) is the vertical anal cleft.

Way of life

The common earthworm lives in meadows and gardens, digs tunnels up to three meters deep and rummages through the ground very intensively. Most of its food consists of plant parts that are not yet strongly decomposed. They are drawn into the living tubes and digested there. The manure is later brought back to the surface or used to solidify the passages.

After about a year, the dewworm becomes sexually mature. The young hatch out of the cocoons after about half a year to a year, depending on food and temperature .

The common earthworm is very suitable as a bio-indicator for the soil quality, as it directly absorbs soil material by digging the passages and eats plant remains as a destructor . The dewworm has been examined as a monitoring organism in the Federal Environmental Specimen Bank (UPB) since 1985 . Thanks to its relatively small number of neurons (around 300), it is a popular research object in the field of neurobiology .

distribution

The worm is native to Europe. In south-east Europe, its distribution on the Balkan Peninsula still reaches North Macedonia and Bulgaria, but it is absent in Greece and Turkey. It is now also found as an invasive species in Canada and the northern United States. Through its consumption of leaves it changes the food chain and through its interactions with seeds it changes the flora there.

Cryptic species

Lumbricus terrestris was first described as one of the first earthworm species by the founder of scientific taxonomy, Carl von Linné , it is the type species of the genus Lumbricus . Due to the early, for today's needs extremely short and vague description, a certain confusion arose about the use of the name, which was resolved by the annelid expert Reginald William Sims by defining a neotype . Unexpectedly, a later investigation using genetic markers, using DNA barcoding , showed that the collective species could be split into two separate lines, which were interpreted as cryptospecies . The old species name Lumbricus herculeus (Savigny, 1826) was reactivated for one line, which was spread more to the south , while the other line, spread more to the north, kept the traditional species name. Lumbricus herculeus was first described as Enteron herculeum in 1826 by the French naturalist Marie Jules César le Lorgne de Savigny , transferred to the genus Lumbricus by Antoine Louis Dugès and has long been considered a synonym of Lumbricus terrestris . Although slight morphological differences are indicated ( Lumbrius herculeus is slightly smaller), the features overlap strongly, so that the species cannot be distinguished after morphological examination. Later, more extensive genetic tests using the nuclear genome supported the existence of two separate lineages, although individual individuals could be interpreted as hybrids between them. Lumbricus herculeus , described from France, is said to occur more in the south, Lumbricus terrestris , described from Scandinavia, more in the north, but the distribution broadly overlaps and specimens of the other line are also available from both regions. The individuals introduced to North America are said to be Lumbricus terrestris s. st. come. Although the justification of the split is not generally disputed, in most regions it has not yet been tested which of the genetic lines and thus possible cryptic species occurs there. For example, it is still unknown in Germany which of the crypto species occur here.

Web links

Commons : Common earthworm (Lumbricus terrestris)  - Collection of images, videos and audio files

Individual evidence

  1. a b Volker Storch, Ulrich Welsch: Kükenthal - zoological internship . 27th edition. Springer Verlag, Berlin, Heidelberg 2014, ISBN 978-3-642-41936-2 , pp. 186-197 .
  2. E. Christian, A. Zicsi: A synoptic identification key of Austria's earthworms (Oligochaeta: Lumbricidae) . In: Soil culture . tape 50 , no. 2 , 1999, p. 121-131 .
  3. RJ Blakemore: Miscellaneous earthworm types in the Natural History Museum, London (Annelida: Oligochaeta: Megadrilacea: Eudrilidae, Lumbricidae, Megascolecidae, Moniligastridae, Octochaetidae) . In: Opuscula Zoologica Budapest . tape 45 , no. 2 , 2014, p. 119-155 ( PDF ).
  4. ^ Reginald W. Sims, Brian M. Gerard: Earthworms: Keys and Notes for the Identification and Study of the Species . In: Linnean Society of London (Ed.): Synopses of the British fauna. New series 31 . Brill, Leiden and Boston 1985, ISBN 978-90-04-07582-5 , pp. 107-109 .
  5. Lumbricus terrestris in the Invasive Species Compendium. Retrieved March 2, 2017 .
  6. İbrahim Mete Misirlioğlu, Ralitsa Teskova, Mirjana Stojanovič (2016): On the presence of Lumbricus terrestris Linnaeus 1758 (Oligochaeta, Lumbricidae) on the Balkan Peninsula: some aspects of ecology and distribution. Turkish Journal of Zoology 40: 438-444. doi: 10.3906 / zoo-1509-12
  7. Global invasive species database, Lumbricus terrestris , accessed January 11, 2020
  8. ^ Samuel W. James, David Porco, Thibaud Decaëns, Benoit Richard, Rodolphe Rougerie, Christer Erséus (2010): DNA Barcoding Reveals Cryptic Diversity in Lumbricus terrestris L., 1758 (Clitellata): Resurrection of L. herculeus (Savigny, 1826) . PLoS ONE 5 (12): e15629. doi: 10.1371 / journal.pone.0015629 .
  9. Svante Martinsson, Christer Erséus (2016): Cryptic speciation and limited hybridization within Lumbricus earthworms (Clitellata: Lumbricidae), Molecular Phylogenetics and Evolution 106: 18-27. doi: 10.1016 / j.ympev.2016.09.011
  10. Ricarda Lehmitz, Jörg Römbke, Stephan Jänsch, Stefanie Krück, Anneke Beylich, Ulfert Graefe (2014): Checklist of earthworms (Oligochaeta: Lumbricidae) from Germany. Zootaxa 3866 (2): 221-245. doi: 10.11646 / zootaxa.3866.2.3
  11. Jörg Römbke, Wolfgang HO Dorow, Stephan Jänsch (2018): Distribution and diversity of earthworms (Lumbricidae) in Hesse (Central Germany): current knowledge. Soil Organisms 90 (3): 171-185.