What is the zoobenthos? Zoobenthos usually are understood as an ecological group of water animals, the most part of the life cycle living at the bottom of reservoirs or in ground. This group is rather specific and unique on its taxonomic, size, ecological, faunistic variety, range of mastered biotops, information, function carrying out in reservoirs of Transbaikalia, etc.
According to the data available now, representatives of Transbaikalia's bottom invertebrate are subdivided to 8 types: Porifera, Coelenterata, Turbellaria, Nematoda and Annelida, arthropods, molluscs. Zoobenthos is representatived from such primitive organisms, as Porifera and Coelenterata (if not to take the Protozoa) up to highly organized representatives of diptera group. All these taxons are characterized by time of occurrence for the Earth - from hundreds millions years ago till now. All species variety of zoobenthos of Transbaikalia (excepting microzoobenthos) at its more full studying will make more than 800 - 1000 species in rather modest estimations.
Concerning dimensional classes, zoobenthos can be divided on micro-, meio- and macrozoobenthos, but still allocated megabenthos. If not to take representatives of microzoobenthos, the range of lenghts of organisms of Transbaikalia's zoobenthos changes from 0,3 millimeters up to 10 and more centimeters (Bivalvia) - that is large than 300 times! According to one of hypotheses the first ecological group of sea metazoa was meiozoobenthos.
Long evolution of animal organisms went in parallel development of the earth's crust and biosphere. Thanking geterotrophic type of feeding, organisms of zoobenthos have become the group having mastered not only fotic a zone, but also afotic a zone of the diversified reservoirs in opposite to phytobenthos . Zoobenthos occupies reservoirs having diverse speed of current, depth, a chemical compound, a temperature mode and is the integrant component practically all types water ecosystem.
The functional role is not limited only the trophic importance. Under favorable conditions zoobenthos takes an active part in destruction fresh organic substance, promoting natural autopurification of waters and preserves ecosystems from destruction or its catastrophic transition to late stages of development. Massive joining of organic substances causes of increasing of zoobenthos's abundance. Thanking its activity large particles of organic matter becomes smaller and are occupied by the bacteria finishing decomposition of organic particles down to mineral elements more actively .