Abstract
The few-bristled worms is an extremely important taxonomic group in terrestrial ecosystems. These worms did not receive earlier the attention they deserve and now we have some deficiencies in the knowledge about their taxonomy, distribution, biology and ecology. Experiments with species of different morphoecological groups of Lumbricidae were spent. We considered that the differences in amplitude and frequency of gizzard smooth muscles contractions between species of Lumbricidae have adaptive character. The contractive activity of the muscles was studied according to the method of isolated preparations. The greatest amplitude and the least frequency of contractions ofvisceral muscles was recorded in detritophages worms of mineral soils. The near-surface species showed the smaller amplitude of muscles contractions, and more greater frequencies of contractions. These physiological distinctions support ideas of the ecological heterogeneity of earthworms. The parameters of contractive activity of smooth muscles of gizzard are the specific physiological variable integrated with the morpho-ecological differentiation of earthworms in natural habitats.