An earthworm substantially enhances physical, chemical, and biological characteristics of soil through their feeding, casting, and burrowing activities. Different earthworm species differ in their ecological strategies which influence main physical features of soil (soil aggregation and porosity) in different degrees and therefore classify them as epigeic, endogeic, and anecic (Lee 1985; Lavelle and Spain 2001; Karaca et al. 2010a; Kizilkaya et al. 2011) (Fig. 21.1). Epigeic species such as Lumbricus rubellus, Eisenia fetida, Dendrodrilus rubidus live in soil humus zone. They are fed from organic materials accumulated above mineral soil layer and therefore occasionally digest mineral soil particles. The typical habitats of epigeic species are manure masses and plant debris layers in forest ecosystems. They build their burrows in organic material layer or in a depth of 0-2.5 cm mineral soil and substantially feed on organic compounds rich in microorganisms. Epigeics are small worms (usually shorter than 7.5 cm) with a reddish brown color. Anecic species such as Lumbricus terrestris, Aporrectodea longa, Dendrobaena platyura are reddish brown color worms with the largest and longest sizes ranging between 12.5 and 20.0 cm. They live in permanent or semi-permanent burrows reached to a depth of 2 m, feed on decaying organic material on soil surface and leave their castings at the mouth of their burrows located on the surface. Endogeic species (Aporrectodea caliginosa, Allolobophora chlorotica, Octolasion lacteum v.b.) live on organic compounds found in mineral soil layers, and inhabit the top 0-50 cm of the soil. They are distinguished from epigeic and anecic species by their distinct color characteristics such as lack of red-brown skin pigmentation and appearance of very pink color on the head and gray color on the body. Adult endogeic species can range from 3 to 12.5 cm (Lee 1985; Lavelle and Spain 2001; Karaca et al. 2010a; Kizilkaya et al. 2011).
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