Earthworms phylum Annelida Clitellata Oligochaeta

There are gt 7000 species known from aquatic and terrestrial habitats, and a small number of species are known to inhabit marine sediments. Most species belong to about 20 families adapted for a terrestrial interstitial habitat. Their distribution is limited by absence of soil organic matter and litter on which they feed. They are absent or rare in arid or cold regions, for climatic as well as nutritional reasons. Their present geographical distribution seems to carry the mark of previous...