Lumbricus rubellus
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 L. rubellus
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| Lumbricus rubellus Linnaeus, 1758 |
Lumbricus rubellus is a species of earthworm. It is usually reddish brown or reddish violet, iridescent dorsally, and pale yellow ventrally. They are usually about 25 to 105 mm in length, and have around 95-120 segments. It is one of the species of earthworm commonly used in vermiculture.
Lumbricus rubellus, or the Red Earthworm, ranges from 25-105mm in length (Edwards and Lofty 1972) and has smooth, reddish, semi transparent, flexible skin segmented into circular sections. Each segment contains four sets 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 the phylum Annelida, while the enlarged segment on the posterior end of the organism called the clitellum identifies the organism as member of the class clitellata. Members of this class are also defined by having permanent gonads.
The habitat Lumbricus rubellus naturally lives in consists of 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 aboitic factors as pH and temperature. Habitat for Lumbricus rubellus is found throughout North America and Europe and it is suspected, but not confirmed, that Lumbricus rubellus can be found in Asia as well (Edwards and Lofty 1972).
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 10.6 degrees Celsius. A further abiotic factor 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).
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.
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 it is to convert 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 in 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] 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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