Lumbricus rubellus
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| Red earthworm | ||||||||||||||||
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 L. rubellus
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| Lumbricus rubellus Hoffmeister, 1843 |
Lumbricus rubellus is a species of earthworm that is related to Lumbricus terrestris. It is usually reddish brown or reddish violet, iridescent dorsally, and pale yellow ventrally. They are usually about 1 to 4 inches (25 to 105 mm) in length, with around 95-120 segments. It is one of the species of earthworm commonly claimed for used in vermiculture although each instance, on proper inspection, has been found to be Eisenia fetida.
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[edit] Size and appearance
Lumbricus rubellus, or the "Red Earthworm", ranges from 1 to 4 inches (25-105mm) 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 and Lofty 1972). 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 denotes membership to Class Clitellata. Members of this class are also defined by having permanent gonads.
[edit] Habitat
Lumbricus rubellus naturally lives in soils high in organic matter, preferably dung and feces (Edwards and Lofty 1972). The worms require loose soil to burrow in and soil moist enough for gas exchange (Wallwork 1983). Further requirements include such abiotic factors as pH and temperature.
Various abiotic factors are significant to Lumbricus rubellus. Reynolds notes that pH is of particular importance, and that a range of 5.5 to 8.7 is acceptable with a preference for neutral soils. Edwards and Lofty note that temperature is also significant, with implications for growth, respiration, metabolism and reproduction amongst other things. They note an ideal temperature of 51 degrees Fahrenheit (10.6 degrees Celsius). A further abiotic factor is moisture, and is noted by Edwards and Lofty as 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 (Edwards and Lofty 1972). With regards to light intensity, Edwards and Lofty note that 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 (Edwards and Lofty).
[edit] Behaviour
The sense organs of Lumbricus rubellus associated with feeding are on the prostomium, located at the anterior end of the organism (Edwards and Lofty 1972). The chemoreceptors here are sensitive to alkaloids, polyphenols and acids. Negative responses are caused by acid and alkaloids (at certain levels), while polyphenol sensitivity identifies different food sources (Edwards and Lofty 1972). Chemoreceptors, as noted by Edwards and Lofty (1983), can also be found on other parts of the organisms body. These serve to direct the organism away from dangers such as temperature or pH variations, and direct the organism towards possible food sources.
[edit] Role in ecosystems
Lumbricus rubellus is a saprophage which feeds on organic material that is in a high state of decomposition (Wallwork 1983). In ecosystems, earthworms such as Lumbricus rubellus increase the rate of transfer between trophic levels 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 (Wallwork 1983).
One significant biotic interaction of Lumbricus rubellus results from a relationship with vitamin B12 producing microorganisms such as bacteria and actinomycetes and barley (Wallwork 1983). 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.
[edit] Medicinal uses
In traditional Chinese medicine, abdominal extracts from Lumbricus rubellus are used in a preparation known as Di Long, or Earth Worm, for treatment of rheumatic, phlegm and blood disorders.
[edit] References
- Edwards, C.A., and Lofty J.R. 1972. Biology of earthworms. Halsted Press, New York, NY.
- Reynolds, J.W., and Dindal, D.L. 1977. The earthworms (Lumbiridea and Sparganophilidea) of Ontario. The Hunter Rose Company, Toronto, Ontario.
- Wallwork, J.A. 1983. Earthworm biology. Edward Arnold Publishers Ltd, London, England.
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