BENTHOS (Greek benthos depth) — set of the organisms inhabiting a bottom of sea and continental reservoirs.
B. includes various bacterial, vegetable and animal forms. Organisms with similar requirements to the habitat form ground communities. In B.'s distribution vertical zonality is noted. In upper zones B. it is most various and rich (the quantity oho can reach 60 kg/sq.m). On a way of life distinguish the organisms which are digging in (worms, clams, maggots), drilling (mollusks, cancroid), motionless (seaweed, sponges, coelenterates), mobile — creeping on a bottom (erinaceouses, Castropoda mollusks, crabs) and times coming off a bottom — so-called somebody - bottom-living forms (cancroid, water insects). On character and a way of food allocate animals of three types: 1) the animals eating the particles weighed in benthonic water; 2) the animals using an organic residues of soil; 3) carnivores.
B. exerts a great influence on chemical and physical. properties of water; the filtration organisms (clams, etc.) promoting clarification of water and types stores of radioelements have practical value. Backboneless animal B. are the power supply for many food fishes (a flounder, sturgeon, salmon). B. has also trade value as the valuable power supply (many algas, crabs, lobsters, shrimps, crayfish, oysters, combs, mussels, trepangs, sea hedgehogs, stars, worms, etc.). For the technical and medical purposes sea and fresh-water mollusks (see), corals, sponges (see), a bloodsucker are used (see). Among bottom-living animals there are also harmful organisms, e.g. wood borers (clams of a teredinida). Many marine organisms, sticking around the bottoms of vessels, obstruct the traffic of vessels, and also cause damage to hydraulic engineering constructions. Some representatives of B. — carriers of dangerous diseases of the person, e.g. a fascioliasis, an oipstorkhoz (fresh-water mollusks); larvae of many blood-sicking insects also belong to B. (midges, gadflies, etc.).
Life of sweet waters of the USSR, under the editorship of V. I. Zhadin, t. 1 — 3, M — JI., 1940 — 1950; Zenkevich L. A. Biology of the seas of the USSR, M., 1963; Zernov S.A. The general hydrobiology, M. — D., 1949, bibliogr.; Ivanov A. V. Trade water invertebrates, M., 1955.
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