Earthworms

of earthworms
earthworm
systematics
Master's group: Urmünder (Protostomia) over trunk: Lophotrochozoen (Lophotrochozoa) trunk: Ringelwürmer (Annelida) class: Belt worms (Clitellata) order: Wenigborster (Oligochaeta) family: Earthworms
scientific name
Lumbricidae
native kinds
Allolobophora Dendrobaena Eisenia Eiseniella Lumbricus Octolasium

the earthworms (Lumbricidae) are in the ground living, arranged worms from the order of the Wenigborster (Oligochaeta). They belong within the trunk (Annelida) of the Ringelwürmer to the class (belt worms) of the Clitellata. Earthworms are a substantial link of the natural cycle soil - plant - humans - soil. From world-wide approximately 3500 kinds 10 kinds with approximately 220 kinds rank that among the family of the Lumbricidae. In Germany at present 39 kinds live. Not all of it are originally here domestic.

The 9 to 30 centimeters long rope worm or common earthworm (Lumbricus terrestris) is beside that 6 to 13 centimeters long compost worm (Eisenia foetida), probably the most well-known native Annelidenart. In the year 2004 the earthworm useful for the nature cycle was explained eddy lots as to “the animal of the yearly”.

name

the name “earthworm” decreases/goes back on the old-high-German term “raining worm” , which refers to the behavior of the worms, with strong rainfalls the underground living tubes rapidly to obviously leave, in order on the earth's surface the water rise in the Oberboden too escape (similar term “rain standard” for earthworm in Denmark usually). , Because to the actual place of residence of the Wurms referred, the English designation “Earthworm ” or the French term “ de Terre” is more appropriate. In other opinion the German name is due not of the characteristic of the worms to come with rains into large crowds to the earth's surface but of its constant underground activity. In 16. Century is to have given it according to still the designation “active worm”.

Which the actual cause for the earthworms is, with rain their living tubes to leave, is obviously not yet completely clarified. One can assume the earthworms do not creep to the earth's surface, because they love allegedly the damp environment of the precipitation, but because they would in particular suffocate with rains, at long lasting rain periods, in their courses in the ground, since the oxygen loosened in the water is not sufficient, in order the worm over the skin respiration with sufficient oxygen to provide. Scientific investigations showed however that even under anaerobic conditions under water earthworms held go only after 35 hours slowly at the basis. As continued to turn out, the worms under these extreme conditions switch to a glykolytischen metabolism without Sauerstoffverbrauch over (anaerobic Glykolyse). Within the bank range of unverbauten waters one finds kinds of earthworm in parts, which quite tolerate and without prejudice to get over a temporary flooding in the Oberboden occasionally also.

figure

segmenting

the bodies of the earthworm consists of numerous cylindrical members (segments), which carry the bristles hardly protruding from the skin at their sides. The bristles, from which earthworms per segment possess 4 pair or 8 pieces, consist of Chitin and proteins and can be moved with the help of special muscles. The number of segments increases with the age of the Wurms. A special growth zone in the proximity Hinterendes produces new members. Attained full growth copies order over around the 160 segments.

skin muscle hose

outward is defined the entire body of the Wurms and concomitantly each of its segments by a skin muscle hose. After a einschichtige epidermis, which some glands - and contains sensory cells and separates outward a Cuticula, a ring muscle layer and a far follow inside the thick longitudinal muscle layer. Most kinds possess skin pigments. So e.g. are. many Lumbricus kinds more or less red colored. All Allolobophora kinds possess against it more dark pigments, which let the skin surface appear rather light-grey or grey.

digesting organs

a kind Oberlippe, also head rag (Prostomium) mentioned, over-curves at the top the mouth. The mouth opening leads into the intestine, which pulls the whole earthworm through from the front to in the back. The intestine begins with a muskulösen Pharynx, after which the esophagus (Oesophagus) with its lime pouches as well as a muskulöser a Kropf and muscle stomach follow. Here (similarly as with chickens ) the vegetable food becomes by included small Steinchen (here: Sandkörner) ground evenly. Follows the long central intestine, which exhibits an a inverting (Typhlosolis) on the back side in its entire length, which helps to increase the internal intestine surface. At the Hinterende of the Wurms is the after. With their kalziumhaltigen elimination products the worms neutralize all taken up acid soil contents materials.

elimination organs

as elimination organs lie in each segment (with exception of the first three members and the last segment) on the left and on the right two Nephridien so by the intestine mentioned, which are enough from, in loops wound Exkretionskanal extending in the final section to the bladder exist themselves. A lash funnel, which rises up into the segment lying before it, catches the substances which can be separated. Each Nephridium is from blood vessels umsponnen, which serve the oxygen supply of the elimination organ. The supply of the cells with oxygen is necessary, because at the loops of the Nephridiums active transportation procedures run off for the elimination of urine acid , urea , ammonium and salts as well as for the back absorption from water , ions and organic compounds.

Coelom

between intestine and skin muscle hose lies in each segment the secondary body cave ( the Coelom). This is distinguished and stout filled with liquid by tender transverse walls (Dissepimente) from the body cave of the neighbour segment. This liquid, which presses from the inside against the skin muscle hose, works as a hydrostatic skeleton and helps the worm when creeping and boring in the ground stability to attain.

nervous system

profile by the head - to legend with click on the picture

the nervous system is highly developed. It is in the brain or upper throat ganglion, which subdivided belly Marks and the Segmentalnerven. The brain consisting of two deformed with one another Cerebralganglien rests upon in the third segment briefly before the beginning of the Pharynx dorsal the intestine. From it numerous nerves pull forward toward Prostomium. Throat konnektive connect the upper throat ganglion on both sides of the front intestine with the Unterschlundganglion lain at the beginning of the fourth segment vent ral of the intestine (see accompanying illustration). The main line of the nervous system follows, that on the ventral side the worm of 4. Head segment up to the tail segment pulls through. It is called therefore belly Mark. In a frontal cut by belly Mark one recognizes that it is derived evolutiv from the cord leader nervous system. The original organization of the cord leader nervous system consists of, lengthwise Konnektiven in pairs running to the body axle, which are connected through transverse to the body axle arranged Kommissuren. Konnektive and Kommissuren are by nerve knot (ganglia), which predominantly of the Zellkörpern of the nerve cells consist, connected. With the earthworm these elements all are united in a median running (unpaaren) nerve strand. In azangefärbten histological preparations one knows the two fiber portions (Kommissuren and Konnektive) as well as the nerve knots on suitable cuts well to differentiate. Per segment branches of belly Marks ever 3 the pair Segmentalnerven off. The front pair lies in the kranialen (kopfwärts oriented) section of a segment, the middle and the rear pair lies usually closely neighbouring in the caudalen (schwanzwärts oriented) range of a segment. This typical arrangement permits in the very most cases to orient a histological after preparation kopfwärts/schwanzwärts. After their branching of belly Marks run the Segmentalnerven first by the secondary body cave earthworm (Coelom) occur then the skin muscle hose, where them itself into a ventralen and isolates a dorsalen branch. In their further process between ring and longitudinal musculature branches continual fine fibers off and inside four the muscle cells, as well as the cells of the epidermis. The innervation of the Dissepimente (muskulöse septa between the segments) takes place via the so-called September valley nerves, those in the shoulders of the front Segmentalnerven from belly Mark branches. The intestine nervous system of the earthworm (also stomodaeales system) was only late discovered relatively. Eyes are missing, but are the earthworm particularly at the front and Hinterende photo-sensitively and reacted also to vibrations of the soil.

blood vessel system

special respiratory organs does not possess the earthworm, but, a closed blood vessel system often branched out, which distributes the oxygen taken up over the skin and the nutrients taken up from the intestine generally speaking bodies. It consists of a back container, which drive the blood from the rear forward, and a belly container. In the segments 7 - 11 becomes the two main blood vessels by muskulöse and strongly kontraktile loops, the so-called. Lateral heart (2 per segment), connected. In the remaining segments there is no more direct connection, between the moving and the belly container. The blood is red colored by the red blood coloring material hemoglobin, which is solved in the blood plasma. It contains also colorless blood corpuscles, the Amoebocyten, which however mostly fit to the gefässwänden. The hemoglobin of the earthworm consists not like that of humans of only 4, but of 24 subunits. Its molecular weight of 3.840.000 is accordingly high and.

way of life

nutrition

of “earthworms are entrails of the earth” (Aristoteles 384-322 v.Chr.). The night-active earthworms are predominantly substrate and herbivores, i.e. they fill their intestine with humus-rich earth and vermodertem plant material. They pull at night for example Keimlinge and sheets into the earth, in order to let and later than food use it rot there. In order to hold the sheets, earthworms can blow up their front end button-like, so that their mouth is as surrounded by a Saugscheibe. This is pressed to the sheet or the Blattstiel, and with the help of the muskulösen Pharynx the worm sucks itself so much firmly that it is able to pull the sucked in sheet backwards creeping into its living tube. Secretions from the Pharynxdrüsen promote the decomposition process. The taken up food is ground afterwards with the help of the muscle stomach and digested in the central intestine. The earthworms eat constant from own area of life this way and that by the Bodenschichten their. The earth taken up thereby contains Detritus - of components, bacteria, mushroom pores and numerous single-celled organisms, which can be digested and used as food. Some kinds verzehren as well known also carrion. By the balance of the earth, which the earthworm creates, the micro organisms useful for the soil are promoted and the soil-hostile are dammed, partially even destroyed.

progressive movement

with the help of its pronounced ring and longitudinal musculature is the earthworm in a the position to move both forward and backwards creeping. The contraction ring muscles Vorderendes for example causes that the following segments become thinner and longer. Diagonally to the rear the arranged bristles embody thereby additionally the kontraktierten segments in the soil. Now from the front to the rear a running contraction follows longitudinal muscles, whereby the segments become again thicker and shorter, which pulls the worm body forward. Contact and light attractions can arrange earthworms also too much rapid muscle contractions in the sense of an escape reaction. With the penetration into the Oberboden, as well as with the building of new, underground living tubes the diluted front end than Bohrinstrument is used. For overcoming the base resistance the firm, hydrostatic pressure serves the body cave liquid.

reproduction

earthworm with circular Clitellum

the earthworms are hermaphrodites and fertilize themselves mutually. Powerful glands, which separate a secretion, contain a certain number of their body segments , which form the belt in such a way specified (the Clitellum, a kind saddle-shaped Verdickung), which together-attaches the two sex partners seal-like with the Begattung. The side edges of the Clitellums particularly step out as so-called puberty borders. During the Begattung two worms with the ventral side put together, so that they can over their genital apertures sperm cellses exchange and into the Receptacula seminis (spherical a inverting for sperm keeping) the sex partner introduce. There in each case the strange sperm cellses stored serve later for the fertilization of the own Eizellen. With some kinds of earthworm now and then also self fertilization was observed. The eggs are put down as with the Blutegeln into Kokons. The secretion of the Clitellum glands serves for the formation of this egg-Kokons. The embryos nourish themselves of the protein, by which they are surrounded, and go through only a small metamorphosis to the worm. The development duration of the young worms can be very different depending upon kind and habitat. Thus the compost worm (Eisenia foetida) in its relatively warm environment slips already after 16 to 20 days, on the other hand Lumbricus needs terrestris at a middle soil temperature of for instance 12° C up to 135 days.

a surviving in the winter

the winter spend most earthworms together-rolled in 40 to 80 cm soil depth in a kind cooling rigidity. Also under heat-storing soil structures such as stumps, stones or Komposthaufen one finds whole colonies of resting worms. Under high and closely closed Schneedecken the soil did not freeze protected from cold weather and usually. Here one can observe now and then earthworms, which are active occasionally even in the winter in the range of the Oberbodens. Still it is unknown to what extent and how long the animals cooling degrees can project. Medium-term in the winter the active worms however the danger threatens to drain, there a moisture penetration of the soil due to the frozen Schneedecke and/or. Bodenoberfläche does not take place. Some kinds can during the winter peace approx. 80% of their original weight lose, before they are received. Lumbricus terrestris e.g. no correct winter peace carries out in the relatively mild areas of South West German country (upper Rhine ditch). It appears in damp to always take up frost-protected nights at the Bodenoberfläche around food. The Kokons put down in the autumn sex-mature earthworms, develop themselves further in the frost-protected soil over the winter. In the spring the young worms slip after entrance of a soil temperature of over 10° C.

meaning for the soil improvement

of earthworms provide for ventilation of the soil

earthworms can within certain ranges a portion of up to 90% of the biomass of the entire Bodenfauna constitute. They take as so-called. Destruenten a central position with the dismantling of organic substances. With their migrations by the soils earthworms of tubes form. In loose soil substrate like e.g.: in damp forest soils or in compost earth the animals do not have problems when penetrating the soil. Mineral soils against it offer very different of resistances depending upon granulation, firmness and current water content. Usually the bored tubes are lined with Schleim and Exkrementen of the worms and stabilized thus for the rapid ascending and descending. One calls this solidification also “wallpaper”. It serves among other things also the plants as fertilizers. The lufthaltigen courses ensure for the fact that aerobe bacteria are supplied with sufficient oxygen and died plant parts better to decompose. In addition, in the vertically bored courses plant roots can grow faster into the depth.

Of special importance a fact is, those already Charles Darwin it observed that earthworms steadily carry the earth originating from the deeper layers of the soil by their intestine through to the earth's surface and thus to the loosening and ventilation of the soils contributes. As accompanying effect is it shown among other things the relieved penetration of water into deeper Bodenschichten. This again promotes that plant growth.

The earthworms set their excrement off usually celestially in the form of geringelten Kotbällchen at the muzzle end of its courses. After Darwins computation the earthworms in many parts of England carry and cause annually on a 6 hectare of large land piece a weight of more than 25,000 kg of earth to the surface thereby a completely substantial mixing of the Bodenschichten, whereby the underground with humus materials is enriched. In the Oberböden of the Tropics and Subtropen still substantially higher conversion rates were determined. It lies near that the soils of the tropical rain forest are here because of the point (up to 280t per hectar).

The purposeful processing of compost (composting) from earthworms (worm compost) results in the so-called as product. Worm humus with highly concentrated components at plant-available nutrients. In the open land are not measurable the positive influences of earthworms, since one cannot separate them from the other environmental influences. Under standardized conditions in the laboratory however, the fruitful effects of these soil inhabitants are occupied. In addition, experiences showed that excessive artificial fertilization affects the Regenwurmfauna rather unfavorably.

Fressfeinde

of earthworms primarily by numerous kinds of bird is pursued. Usually there is stars, throttles, blackbirds and crows, that pursue the worms purposefully. Further natural enemies are Marder, moles, hedgehogs, pointed mice, earth toads, frogs, Feuersalamander, Hundertfüsser, ants and run beetles. Also foxes and Dachse nourish themselves gladly of earthworms.

Moles bite the earthworms frequently in the front end, in order to prevent it from the Davonkriechen. Stuck, but the still lebensfähigen worms become in this way, afterwards at a safe place underground deposited over as food reservoir to function (e.g. as winter supply).

parasites

in earthworms live numerous parasitize-end organisms. Beside different, partially symbiontisch living bacteria, Ciliaten and Flagellaten particularly frequently Gregarinen (Sporozoen) are and thread worms (Nematoden). Above all the body cave as well as the Samenblase are struck. Most parasites are however transferred harmless nature, some diseases serious as intermediate landlords (e.g. the lung worm illness with pigs and chickens by Metastrongylus - kinds). Now and then also larvae are proven by tapeworms (Eucestoda) in earthworms. Occasionally also larvae of the gold fly ( Lucilia sericata) in earthworms parasitieren. They keep themselves preferential within the front range of the earthworm (3. and. 4. Segment) up and lead after some time to the death of their landlord. On the basis these facts it sounds surely plausible that earthworms are not necessarily suitable for the human consumption.

endangerment and protection

endangerment by complete sealing of the Bodenoberfläche by construction of roads and road

„…A worm am I - no more humans - Gespött of the people, all treat me like dirt… “already deplored king David its personal situation in Psalm 22 of the old person of will. Also in our time numerous dangers threaten the earthworm and in particular its habitat the soil, like e.g. by harmful soil changes. Harmful Stoffeinträge into the soils can be caused by very different sources. The pollutants originate to different portions from private like commercial plants, from the traffic, from the utilization and yield of sewage sludge and wastes as well as from inappropriate use of fertilizing and plant protection agents. All factors mentioned cause a change and/or. a sinking of the natural soil functions. Of it nutrient-poor and flachgründige locations, which possess by nature a smaller buffer ability in relation to harmful soil changes, are particularly concerned. Due to the general damage the soils bind less and less humus portions and mineral materials. The soil life comes finally to succumbing, this leads gradually to the complete erosion of the Oberbodens by wind and rain.

Further problems bring the compression and those ever more increasing sealing of our soils with itself. One stated that under completely sealed surfaces such as roadways and parking lots no more soil organisms exist. The Enquete commission German of Bundestag “protection of humans and the environment” dares the prognosis in its interim report (“concept lastingness”) that widens surfaces federal territory in approx. Will be 80 years course-built, if the utilization of land will walk by settlement and traffic as in the last 30 years further in front.

It is obvious to pay attention when planning of new living and trade areas to a surface-saving building method with as small a surface sealing as possible. , As well as the plant of green areas and hedge courses it makes the multiple use of tree disks for turf sods possible it that earthworms and other soil organisms themselves can exist in densely populated centers of dense development.

can be kept relatively

simple to worm breed, worm farm most kinds of earthworm in shank and increased accordingly well. In this way earthworms become in many places in so-called. Worm farms on a large scale bred and commercially used. The worms find multiple use as fodder animals in the zoo specialized trade or as seals for the angler.

Breed beginnings and accessories to the worm breed can be ordered by enterprises in the Internet, specialized in it, and dispatched on the post office way.

Worm cultures are used for some time also for the soil improvement and for the compost economy. Best own itself for this kinds, which exhibit already by nature high conversion and reproduction rates (e.g. Eisenia foetida).

Recently also tropical kinds of earthworm in heated plants are cultivated (e.g. Eudrilus eugeniae from west Africa). Such kinds should be bred however only within closed ranges (greenhouses, laboratory units). A yield in the open land should not take place due to the Neozoenproblematik. Also for the hobby gardner and the owner of Terrarientieren (e.g. ) Itself the breed of earthworms in so-called knows turtles, frog and salamanders. Worm crates are worth. These special containers are suitable among other things also for the list on balconies and terraces.

Reports emerge again and again in the press that earthworms for the human consumption are bred and offered (e.g. as Fleischklös - so-called. “Wormburger” or freshly frittiert). Due to generally strong parasitizing of the worms here however caution is required (S. Chapter. Parasite).

Thielemann' sches Oktett

the Thielemann' sche Oktettmethode is one in the science in the meantime recognized application, to the catch of earthworms by means of electric current. The procedure very early of the deceased biologist Dr. Ullrich Thielemann is used frequently in the framework from investigations to the standardized inventory collection of the Regenwurmfauna of special locations. Also in the course of the bio monitoring it is a wide-spread checking method. Here one pushes 8 electrodes with a distance from approx. 50 cm to each other in a circle into the Oberboden. Put on depending upon conductivity of the lining up soil “zerhackte ” direct current impulses from 50 to 250 V to the electrodes for the duration by approximately 20 minutes. Within fewer minutes the earthworms from the soil, settled in the electrical field, are driven, whereby the larger copies creep mostly first to the surface.

when leaving its living tube (night photograph)

in Germany 39 kinds from 6 kinds are systematic overview of the kinds

a rope worm (Lumbricus terrestris ), occurring in Germany, at present:

Kind Allolobophora - (14 kinds):

kind Dendrobaena - (9 kinds):

kind Eisenia (4 kinds):

kind Eiseniella (1 kind):

E.tetraedra

kind Lumbricus (8 kinds (9)):

kind Octolasium (3 kinds):

European names (trivial names)

of earthworms in the popular culture

the probably most well-known earthworm is the unorthodox video game hero Earthworm Jim. The joke at the figure is that this becomes actually quite limited working animal species suddenly a shoot-joyful superhero. In addition earthworms play a Nebenrolle in the Comic and indication trick row Orson's farm of Jim Davis, in which they must evade and escape to the attacks of the hungry Küken steadily. Admits is also earthworm max from the TV serial bee Maja.

see also

Desertifikation, Edaphon, Terra preta

to literature (selection)

• Peter, W. & V. Barrier village: The earthworm. Heidelberg 1986.
• Book, W.: The earthworm in the garden. Stuttgart: Ulmer, 1986.TB ISBN 3800162768
• J.E. Satchell: Earthworm Ecology, London 1983.
• Greener, B. & E. Zebe (1978): Studies on the anaerobic metabolism OF earthworms. Complete one. Biochem. Physiol 60 B, 441-445.
• O, G. (1982): The “giant earthworm” (Lumbricus badensis) of the south black forest. In: The field mountain in the Black Forest. Nature and landscape protection areas bath. - Peppers. 12: S. 394-396, Karlsruhe.
• Charles Darwin (1882): The formation of the field earth by the Thätigkeit of the worms with observation over their way of life. - Berlin and. Bad ways - [reproduction 1983 of the edition of 1882].
• Thielemann, And. (1986): Electrical earthworm catch with the Oktett method. Pedobiologia 29 (4), 296-302.
• Breidenbach, J.: Normal anatomy and - histologie of the Lumbriciden Lumbricus terrestris L. Thesis on-line one (2002): http://miami.uni-muenster.de/servlets/DocumentServlet?id=117

Web on the left of

• exhibition earthworm
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• ABC that eddy lots: The earthworm - self learning course for pupils
• in 10 steps to the own worm breed

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