Of European nature, Reds are a good deep red in colour, with the clitellum commencing at segments 32.The clitellum is raised and runs over the back, from belly to belly, like a saddle. The anterior is a darker red and, when retracted, is termed bullnose. Reds characteristically flatten their tail (for enhanced grip) as they push themselves forward, and are sometimes called flat tails. When flattened like this, the tail is quite pointed in a shape similar to a bricklayers trowel. In soil Reds will always be found in the top 15cm, where the soil is very moist and high in organic matter.
Reds 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 Further requirements include such abiotic factors as pH and temperature.
Various abiotic factors are significant to Reds. pH is of particular importance; a range of 5.5 to 8.7 is acceptable with a preference for neutral soils. 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 Reds 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.
Reds in the Ecosystem
The Red earthworm is a saprophage which feeds on organic material that is in a high state of decomposition.In ecosystems, earthworms such as Reds increase the rate of transfer between tropic levels by making it easier for plants to uptake nutrients. In food chains, earthworms such as Reds 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 Reds results from a relationship with vitamin B12 producing microorganisms such as bacteria and actinomycetes and barley. The presence of such earthworms as Reds 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 Reds.
The sense organs of Reds associated with feeding are on the prostomium, located at the anterior end of the organism. 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. Chemoreceptors 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 to direct the organism towards possible food sources.