Abstract:
We considered that the morphoecological differences between species of Lumbricidae
have adaptive character. For our research, the amplitude and frequency of contractions of the visceral
(gizzard) smooth muscles were selected. The contractive activity of the muscles was studied
according to the method of isolated preparations. The greatest amplitude of contractions
(86.71±3.66 per mg) was recorded in worms of mineral soils for Aporrectodea caliginosa caliginosa
in which the frequency of contractions of visceral muscles was 2.46±0.58 contr/min. Apparently,
in detritophages the gut muscles push the dense food mass, but their contractions are not
more frequent than 2-3 times a minute. The muscles of the surface-living A. caliginosa trapezoides
showed smaller amplitude, 49.58±2.56 per mg, and frequencies were 4.89±0.37 contr/min.
This subspecies ingested decaying vegetative remains, which entered their intestines as loose food
mass completely accessible to digestion. Earthworms inhabiting mineral soil layers have greater
amplitude of gut muscle contractions than the leaf-litter species, which is probably influenced by
differences in their diet. We can conclude that parameters of spontaneous contractive activity of
smooth muscles of the A. caliginosa digestive tract are related to the subspecies’ life characteristics
in biocenosis. These parameters are stable characteristics of the forms adapted to consumption
of certain types of food resources in natural habitats.
