''Lumbricus rubellus'' is a species of

earthworm An earthworm is a terrestrial invertebrate that belongs to the phylum Annelida. They exhibit a tube-within-a-tube body plan; they are externally segmented with corresponding internal segmentation; and they usually have setae on all segments. Th ...

that is related to ''

Lumbricus terrestris ''Lumbricus terrestris'' or the ''common earthworm'' is a large, reddish worm species thought to be native to Western Europe, now widely distributed around the world (along with several other lumbricids). In some areas where it is an introduce ...

''. It is usually reddish brown or reddish violet, iridescent dorsally, and pale yellow ventrally. They are usually about to in length, with around 95–120 segments. Their native distribution was mainland Europe and the British Isles, but they have currently spread worldwide in suitable habitats.

Size and appearance

''Lumbricus rubellus'', or the "red earthworm", ranges from to in length and has smooth, reddish, semi-transparent, flexible skin segmented into circular sections. Each segment contains four pairs of setae, or bristles, and the total number of segments per matured organism ranges from 95–105.Edwards, C.A., and Lofty J.R. (1972). ''Biology of earthworms''. Halsted Press, New York, NY. The segmentation of ''Lumbricus rubellus'' identifies the organism as a member of Phylum Annelida, while the enlarged segments towards the anterior of the organism called the

clitellum The clitellum is a thickened glandular and non-segmented section of the body wall near the head in earthworms and leeches, that secretes a viscid sac in which eggs are stored. It is located near the anterior end of the body, between the fourteent ...

denotes membership to Class Clitellata. Members of this class are also defined by having permanent

gonads A gonad, sex gland, or reproductive gland is a mixed gland that produces the gametes and sex hormones of an organism. Female reproductive cells are egg cells, and male reproductive cells are sperm. The male gonad, the testicle, produces sperm ...

Habitat

''Lumbricus rubellus'' naturally lives in soils high in organic matter, preferably dung and feces. The worms require loose soil to burrow in and soil moist enough for gas exchange.Wallwork, J.A. (1983). ''Earthworm biology''. Edward Arnold Publishers Ltd., London, England. Further requirements include such abiotic factors as pH and temperature. Various abiotic factors are significant to ''Lumbricus rubellus''. pH is of particular importance; a range of 5.5 to 8.7 is acceptable with a preference for neutral soils.Reynolds, J.W., and Dindal, D.L. (1977). ''The earthworms (Lumbiridea and Sparganophilidea) of Ontario''. The Hunter Rose Company, Toronto, Ontario. Temperature is also significant, with implications for growth, respiration, metabolism and reproduction amongst other things. An ideal temperature is 51 degrees Fahrenheit (10.6 degrees Celsius). A further abiotic factor is moisture, which is important for respiration. A similar species, ''Millsonia anomala'', was most active at 10–17% moisture content. The substratum for ''Lumbricus rubellus'' is related to the species food sources and pH and moisture requirements. Dung is the species preference. With regards to light intensity, most earthworm species are photonegative to strong sources of light and photopositive to weak sources of light. This is attributable to the effects of intense light, such as drying and a lack of food sources found above ground for earthworms.

Behaviour

The sense organs of ''Lumbricus rubellus'' associated with feeding are on the prostomium, located at the anterior end of the organism. The

chemoreceptor A chemoreceptor, also known as chemosensor, is a specialized sensory receptor which transduces a chemical substance (endogenous or induced) to generate a biological signal. This signal may be in the form of an action potential, if the chemorecept ...

s here are sensitive to

alkaloid Alkaloids are a class of basic, naturally occurring organic compounds that contain at least one nitrogen atom. This group also includes some related compounds with neutral and even weakly acidic properties. Some synthetic compounds of similar ...

polyphenol Polyphenols () are a large family of naturally occurring organic compounds characterized by multiples of phenol units. They are abundant in plants and structurally diverse. Polyphenols include flavonoids, tannic acid, and ellagitannin, some of ...

s, and acids. Negative responses are caused by acid and alkaloids (at certain levels), while polyphenol sensitivity identifies different food sources. Chemoreceptors can also be found on other parts of the organism's body. These serve to direct the organism away from dangers such as temperature or pH variations, and to direct the organism towards possible food sources.

Role in ecosystems

''Lumbricus rubellus'' is a

saprophage Saprotrophic nutrition or lysotrophic nutrition is a process of chemoheterotrophic extracellular digestion involved in the processing of decayed (dead or waste) organic matter. It occurs in saprotrophs, and is most often associated with fungi ( ...

which feeds on organic material that is in a high state of decomposition. In ecosystems, earthworms such as ''Lumbricus rubellus'' increase the rate of transfer between

trophic level The trophic level of an organism is the position it occupies in a food web. A food chain is a succession of organisms that eat other organisms and may, in turn, be eaten themselves. The trophic level of an organism is the number of steps it i ...

s by making it easier for plants to uptake nutrients. In food chains, earthworms such as ''Lumbricus rubellus'' are primary consumers whose role is converting the energy synthesized by photosynthetic plants into food for animals at higher trophic levels. One significant biotic interaction of ''Lumbricus rubellus'' results from a relationship with vitamin B₁₂-producing microorganisms such as bacteria and actinomycetes and barley. The presence of such earthworms as ''Lumbricus rubellus'' increases concentrations of vitamin B₁₂-producing microorganisms and vitamin B₁₂ in the soil. The result is an increased barley yield and an increased volume of organic material for the earthworms. In this way a positive feedback relationship exists between the barley, microorganisms and ''Lumbricus rubellus''.

Medicinal uses

traditional Chinese medicine Traditional Chinese medicine (TCM) is an alternative medical practice drawn from traditional medicine in China. It has been described as "fraught with pseudoscience", with the majority of its treatments having no logical mechanism of action ...

, abdominal extracts from ''Lumbricus rubellus'' are used in a preparation known as '' Di Long'', or Earth Dragon, for treatment of rheumatic, phlegm and blood disorders.

References

External links

Article on ''Lumbricus rubellus''EST project for L. rubellus
{{Authority control Lumbricidae Coprophagous animals Animals described in 1843