Benthos (from Greek bénthos - depth)

the totality of organisms living on the ground and in the ground of marine and continental bodies of water. In contrast to B., organisms living in the water column and not connected to the bottom are called pelagic organisms (see Pelagic organisms) (neuston, pleiston, plankton and nekton). B. is divided into animal (zoobenthos) and vegetable (phytobenthos). According to the method of living at the bottom of the reservoir in zoobenthos, animals living in the ground and on the ground, mobile, inactive and immobile, partially embedded in the ground or attached ( fig. ) According to the method of nutrition, representatives of zoobenthos are divided into predatory (carnivorous), herbivorous, detrital (eating organic particles), etc. Many animals living at the bottom of the reservoir are difficult to attribute to pelagic or benthic and they are called planktobenthos and nectobenthos. In size, benthic organisms are divided into large (macrobenthos), medium (mesobenthos) and small (microbenthos). The term meiobenthos is also used - small B. without bacteria.

In the seas, zoobenthos is mainly represented by foraminifera, sponges, intestinal, nemerthins, polychaete worms, sipunculides, bryozoans, brachopods, mollusks, crustaceans, echinoderms, ascidians, and fish. The bulk of zoobenthos is confined to shallow areas. On the littoral (See Litoral) and in the upper horizon of the sublittoral zone (see Sublittoral) the mass of animal organisms in an area of \u200b\u200b1 m 2 can reach many tens of kilograms (mainly mollusks). At depths up to 100-150 m B. biomass is hundreds and tens of grams; at a depth of 500-1000 m B. biomass is also sometimes calculated in grams, deeper - in fractions of a gram, at great depths (Abyssal) - milligrams. Vertical zoning is also observed in the B distribution: mollusks and crustaceans predominate in the upper horizons, mollusks, polychaetes and echinoderms in the middle horizons, and polychaetes, crustaceans and echinoderms in the deeper ones.

Most plant organisms in the seas are bacteria and algae (diatoms, green, brown and red). Near the coasts, some flowering plants are also common: zoster, phylospadix, rupiah, etc. Phytobenthos is the richest and most diverse on rocky and rocky bottom sections, which serve as a solid substrate for the attachment of algae. Along the Murmansk, White Sea and Far East coasts, algae from kelp and fucus (from brown) often give a mass of 15-30 kg on the 1 m 2 bottom in the littoral and upper sublittoral horizon. Thickets of red alga phyllophora are known in the northwestern part of the Black Sea at a depth of 20-60 mwhere its mass is on average 1.7 kgon 1 m 2 bottom, and in general - millions of tons. On soft soils, phytobenthos develops only in shallow areas, more or less protected from the action of waves. Here it consists mainly of flowering plants (zoster, etc.), the root system of which allows them to take root in sandy and silty soils.

The vertical distribution of algae depends on the composition of the solar spectrum, reaching different depths due to the uneven absorption of rays with different wavelengths; green algae are usually concentrated in the upper horizon, brown algae below, and mainly red algae below.

In fresh water bodies the amount of zoobenthos is much less than in marine ones, and its composition is uniform; it includes protozoa, sponges, ciliary and small-worm worms, leeches, bryozoans, mollusks and insect larvae. Sometimes it consists mainly of larvae of chironomids and oligochaetes, giving 1 m 2 a mass of several tens of grams and representing a very large feed value for fish. The composition of plant B. freshwater reservoirs includes bacteria, diatoms and green algae (char and nitrous algae), as well as numerous coastal plants located clearly marked belts in the direction from the coast. The first belt consists of semi-immersed plants (reeds, reeds, cattail, sedges, etc.); the second - from submerged plants with leaves floating on the surface of the water (water lilies, egg capsules, etc.); the third belt is from submerged plants, in which usually only flowers rise above water ( for the most part pest, elodei, etc.).

A significant part of marine B. is used as food or used as technical raw material. Among the animals are mollusks (oyster, mussel, etc.) and crustaceans (crabs, shrimps, lobsters, etc.). Out of 12 million c of marine invertebrates harvested annually, 62% are mollusks and 30% are crustaceans. Many mollusks have fodder significance for fish and, in addition, produce mother of pearl and pearls. Among other animals of B., toilet sponges and noble coral are of great commercial importance.

Some bottom animals are harmful. First of all, these are Sea woodworms. (bivalve mollusks of Teredinidae). Many marine organisms in large numbers settle on the bottom of the ships, reducing the speed of ships. From plants of marine B. are used as food and technical raw materials: kelp, ulva, porphyry, anfelzia, phyllophora and zoster. Some plants that make up freshwater B., for example reeds, reeds, etc., are used in industry and agriculture. An increase in the amount of freshwater phytobenthos is sometimes harmful, because leads to overgrowing of the pool; the means of struggle is mowing.

Lit .: Zhadin V.I., Fauna of rivers and reservoirs, M.-L., 1940; The Life of Fresh Water of the USSR, ed. V. I. Zhadina, t. 1-4, M.-L., 1940-59; Voronikhin N.N., Vegetable world Ocean, M.-L., 1945; Zenkevich L.A., Fauna and biological productivity Sea, t. 1-2, M., 1947-51; him, Biology of the Seas of the USSR, M., 1963; 3ernov S. A., General hydrobiology, 2nd ed., M.-L., 1949; Konstantinov A.S., General hydrobiology, M., 1967.

L.A. Zenkevich, T.F. Shchapova.

Various representatives of marine benthos. Bottom-moving organisms: Carcinus crab (2); starfish Asterias (3). Organisms, sometimes lying on the bottom, then floating: stingray (4); flounder (5). Sedentary organisms: mollusks - chiton (6); scallop (Pecten) (9); saucer (Patella) (11). Organisms attached or lying on the bottom: oysters (8). Organisms that dig into the ground: lancelet (15); clam mua (16). Rock drilling organisms: Pholas mollusk (12). Fixed organisms: corals building reefs (1); crustacean - sea acorn (Balanus) (7); Phallusia ascidia (10); Euplectella glass sponge (13); tubular worm Spirografis (14); Tabularia hydroid (17); sea \u200b\u200blily (18).

Big soviet encyclopedia. - M .: Soviet Encyclopedia. 1969-1978 .

See what "Bentos" is in other dictionaries:

- (from Greek. benthos depth), benthic organisms, a set of organisms living on the bottom of reservoirs adapted to the appropriate substrate (litho, psammo, pelo, argillo, phytophilic species). Benthos is divided into plant (phytobenthos), ... ... Ecological Dictionary

- (from the Greek. benthos depth) the totality of organisms that live on the ground and in the ground bottom of water bodies. Sea benthos serves as food for many fish and other aquatic animals, and is also used by humans (e.g. algae, oysters, crabs, some fish) ... Big Encyclopedic Dictionary

- (from Greek. benthos depth), a set of organisms that live on the ground and in the ground of marine and continental bodies of water. B. is divided into plant (phytobenthos) and animal (zoobenthos). In zoobenthos distinguish animals living in the thickness of the soil ... ... Biological Encyclopedic Dictionary

BENTOS, flora and fauna of bottom or bottom sections of the sea. The fauna includes motionlessly attached forms, such as sponges, crabs and snails freely moving along the bottom, as well as buried in the ground, such as worms, as well as countless ... ... Scientific and technical encyclopedic dictionary

The set of organisms that live on the ground and in the ground of water bodies. (Source: “Microbiology: Glossary of Terms”, Firsov NN, M: Bustard, 2006) ... Dictionary of Microbiology

Exist., Number of synonyms: 7 macrobenthos (1) mesobenthos (1) microbenthos (1) ... Synonym dictionary

Organisms that inhabit the bottom of the reservoir. There are halobenthos inhabiting the bottom of the sea, and limnobenthos inhabiting the bottom of fresh water. Depending on the lifestyle of animals B. can be sedentary and mobile. Geological dictionary: in 2 volumes. M .: Subsoil ... Geological Encyclopedia

Benthos - a set of macroorganisms living at the bottom of reservoirs ... Source: MU 1.2.2743 10. 1.2. Hygiene, toxicology, sanitation. Sampling procedure for the identification and identification of nanomaterials in water bodies. Methodical instructions (approved. ... ... Official terminology

The set of organisms that live at the bottom of water bodies. It consists of organisms of different trophic groups: * producers (microscopic and large algae, flowering plants and horsetails); * detritophages eating the remains of dead animals and ... ... Glossary of Business Terms

BENTHOS - (from the Greek. benthos depth), a community of marine or freshwater plants and animals, covering those forms of them, which in their development are closely related to the surface of the bottom, coasts and various underwater objects. KB relate as forms motionless ... ... Big Medical Encyclopedia

benthos - Organisms leading a benthic lifestyle. B. can be sedentary and mobile. [Dictionary of geological terms and concepts. Tomsk State University] Topics geology, geophysics General terms geological activity marine-exogenous ... Technical Translator Reference

Books

• Life at the bottom. Bio-geography and bio-ecology of benthos, O. V. Maksimova. The book analyzes various approaches and views on the structure of the biosphere mainly on the example of the biogeography and ecology of marine benthos. The main aspects of biology are considered ... Publisher:

Water is the habitat of many living organisms. Many organisms remained to live in the ocean or in freshwater bodies. The ocean was and remains the scene of the development of a vibrant and diverse life. It is inhabited by 300 thousand species of animals and microorganisms and 30 thousand plant species.

Why is there such a big difference in species composition Flora and fauna of the oceans? The fact is that animals inhabit the entire thickness of the ocean, and plants can live only to a depth of 100 m, where the sun's rays reach. And although compared to the thickness of the ocean, the stometer depth does not seem very significant, it is this layer that ensures life in it.

Living organisms in the ocean and fresh water bodies are divided into three groups: plankton, nekton and benthos.

Plankton (from greek planktos - wandering) - these are all organisms that inhabit fresh and salt bodies of water and are almost incapable of independent movement (Fig. 167). They live in a suspended state, as if soaring, because they do not have movement organs capable of withstanding the movement of water, such as currents. The size of these inhabitants ranges from microscopic to several centimeters. Plankton is divided into animal - zooplankton and growing - phytoplankton.

It is clear that representatives phytoplankton - algae capable of photosynthesis inhabit oceans and seas only to a depth of 100 m. Phytoplankton serves as food for zooplankton and other aquatic animals.

Fig. 168. Humpback Whale

Zooplankton distributed throughout the water column. It is represented by small crustaceans, protozoa, intestinal, eggs, and fish larvae. Most planktonic organisms are characterized by adaptations for soaring in the water column: long outgrowths, gas or fat inclusions, gelation of the body, etc.

Various small fish feed on plankton ( sardines, anchovies and etc.). And not only. This is a favorite delicacy of the largest marine animals - whales (Fig. 168), which absorb a huge number of these smallest inhabitants of the ocean, constantly passing water through the plates of a whalebone.

Nekton (from greek nektos - floating) - actively floating aquatic animals that are able to withstand the force of the current and move over considerable distances. These include fishCal Mars cetaceans, pinnipeds, water snakes, turtles, penguins and etc. Material from the site

Benthos (from greek benthos - depth) - organisms that live on the ground and in the soil of the bottom of rivers, seas and oceans. Actively moving benthos animals include sea \u200b\u200bstars, crabs, crayfish (Fig. 169). There are organisms that either float or lie at the bottom, - flounders (Fig. 170) and ramps. Sedentary mollusks ( scallops, saucers) Oysters and other mollusks are attached to the bottom, and buried in the ground lancelet. The bulk of benthos lives in shallow areas of the seas.

On this page, material on the topics:

• Ocean Benthos Information

• Bentos Report

• Plankton nekton benthos how to move

• Report on plankton nekton benthos

• Bentos Presentation

Questions about this material:

What is a bentos? How to spell given word. Concept and interpretation.

Benthos BENTOS (from the Greek. Benthos - depth), a set of organisms that live on the ground and in the ground of marine and continental bodies of water. B. is divided into plant (phytobenthos) and animal (zoobenthos). In zoobenthos, animals living in the soil are distinguished - infauna (Ch. Arr. Many polychaete worms and bivalve mollusks, echiurids, sipunculides, certain echinoderms, etc.) moving along the surface of the soil - onfauna (polychaete worms and mollusks, most , decomposed crustaceans), attached to the substrate - epifauna (sponges, hydroids, sea anemones and decomposed corals, bryozoans, sea acorns, some bivalves, etc.), as well as swimming near the bottom and only periodically sink to the bottom - nectobenthos (shrimp, mysids, some holothurians, bottom fish, etc.). In terms of size, macrobenthos are distinguished among B. organisms - from 5-10 mm and larger (the vast majority of bottom animals), meiobenthos - from 0.5 to 5-10 mm (population of the very top, soil layer) and microbenthos - less than 0.5 mm (bacteria and other unicellular organisms). The basis of shallow phytobenthos in the seas is macrophytes (algae and marine grasses); therefore, clusters of bottom diatoms can also play a role. In addition to animals, only bacteria and lower fungi live in the depths. B. biomass in the seas decreases with depth: on the littoral and up, sublittoral - up to 5-10 kg / m2 or more, deeper, in the sublittoral - hundreds and tens of g / m2, in batial - grams, in abyssal - usually not more than 1 g / m2, and in life-poor centers, districts of the oceans - 0.01 g / m2 and less. Shallow waters (up to 200 m), which occupy less than 8% of the ocean floor area, are located in the vicinity of the continents. 60% of the total oceanic biomass B., and the share of the abyssal (deeper than 3000 m), which occupies 3 / “of the bottom area, is only less than 10%. Total biomass B. in the ocean is estimated at 10-12 billion tons. In some districts of the east. parts of the Pacific approx. to the deep. 2.5-3 km discovered (in 1979) the so-called. oases of life near the exits of hot groundwater (hydrotherm). In these areas, B. biomass reaches several. kg / m2; their fauna includes many previously unknown animal species: giant bivalve mollusks and pogonophore representatives. In fresh water reservoirs, B. is qualitatively and quantitatively poorer than in marine ones. Of the animals it includes protozoa, sponges, roundworms, small-worms, leeches, mollusks, crustaceans and many other larvae. aquatic insects. Phytobenthos is presented by hl. arr. algae (especially blue-green and char) and decomp. flowering plants (buds, water lilies, cattail, reed, etc.). B. serves as food for many. fish, and in the seas also for certain pinnipeds. Mn types of shallow pestilence. B. - object of fishing and aquaculture. . (Source: “Biological Encyclopedic Dictionary.” Edited by M. S. Gilyarov; Editorial: A. A. Babaev, G. G. Vinberg, G. A. Zavarzin et al. - 2nd ed., Corrected. - M .: Sov. Encyclopedia, 1986.) a living organism of living organisms living on the bottom and in the ground of water bodies. The basis of phytobenthos (the plant component of benthos) in the seas and oceans are green, brown and red algae. The composition of freshwater benthos is dominated by green algae and higher plants. Organisms of zoobenthos (the animal component of benthos) can inhabit the soil (e.g. polychaete worms), be attached to a substrate (e.g. corals, sponges) or move freely along it (e.g. crustaceans). In the zoobenthos of the seas and oceans, foraminifera, sponges, corals, polychaete worms, mollusks, crustaceans, echinoderms, fish, etc. prevail. fresh waters zoobenthos is usually represented by protozoa, sponges, worms, leeches, mollusks, insect larvae, etc. Benthos serves as food for many commercial fish (benthophages), and in the seas for some pinnipeds. Many benthos organisms are used in the food and light industries .. (Source: “Biology. Modern Illustrated Encyclopedia.” Edited by A.P. Gorkin; M .: Rosman, 2006.)

Plankton, nekton, benthos - three groups into which all aquatic living creatures can be divided. Plankton form algae and small animals that swim near the surface of the water. Necton consists of animals that can actively swim and dive in the water, these are fish, turtles, whales, sharks and others. Benthos are organisms that live in the lowest layers of the aquatic environment. It includes animals that are ecologically related to the bottom, including many echinoderms, bottom fish, crustaceans, mollusks, annelids, and so on.

Types of marine life

They are divided into three groups: plankton, nekton, benthos. Zooplankton is represented by drifting animals, which are usually small in size, but can grow to fairly large sizes (for example, jellyfish). Zooplankton may also include temporary larval forms of organisms that can grow and leave planktonic communities and join such groups as nekton, benthos.

The nekton class makes up the largest part of the animals living in the ocean. A variety of fish, octopuses, whales, moray eels, dolphins and squids are all examples of nekton. This large-scale category includes a number of very diverse creatures that are very different from each other by many criteria.

What is benthos? The third type of marine animals that spend their entire lives at the bottom of the ocean. This group includes lobsters, starfish, all kinds of worms, snails, oysters and many others. Some of these creatures, such as lobsters and snails, can independently move along the bottom, but their lifestyle is so closely connected with the ocean floor that they could not survive far from this environment. Benthos are organisms that live on the bottom of the ocean and include plants, animals, and bacteria.

Plankton - the most common form of life in the aquatic environment

When you imagine life in the ocean, usually all associations are somehow connected with fish, although in fact fish is not the most common form. The largest group is plankton. The other two groups are nekton (actively swimming animals) and benthos (these are living organisms that inhabit the bottom).

Most plankton species are too small to be seen with the naked eye.

There are two main types of plankton.

• Phytoplankton, which produces food through photosynthesis. Most of them are various algae.
• Zooplankton, which feeds on phytoplankton. It includes tiny animals and fish larvae.

Plankton: general information

Plankton are microscopic inhabitants of the pelagic environment. They are the most important components of food chains in the aquatic environment, as they provide food for nekton (crustaceans, fish, and squid) and benthos. They also have a global impact on the biosphere, since the balance of the components of the Earth’s atmosphere depends to a large extent on their photosynthetic activity.

The term "plankton" is derived from the Greek planktos, which means "wandering" or "drifting". Most of the plankton spends its existence, swimming along with ocean currents. However, not all species go with the flow, many forms can control their movements, and their survival depends almost entirely on their independence.

Sizes and representatives of plankton

In size, plankton ranges from tiny microbes, whose length is 1 micrometer, to jellyfish, whose gelatinous bell can reach 2 meters in width, and tentacles can extend more than 15 meters. However, most planktonic organisms are animals less than 1 millimeter in length. They exist due to nutrients in seawater and due to photosynthesis.

Representatives of plankton are a wide variety of organisms, such as algae, bacteria, protozoa, the larvae of some animals and crustaceans. Most planktonic protists are eukaryotes, predominantly unicellular organisms. Plankton can be divided into phytoplankton, zooplankton and microbes (bacteria). Phytoplankton carries out photosynthesis, and zooplankton is represented by heterotrophic consumers.

Nekton

Representatives of nekton are active swimmers and often the most famous organisms in sea \u200b\u200bwaters. These are the main predators in most marine food chains. The distinction between nekton and plankton is not always sharp. Many large animals (for example, tuna) spend their larval stage in the form of plankton, while in the adult stage it is quite large and active nekton.

The vast majority of nekton are vertebrates; these are fish, reptiles, mammals, mollusks and crustaceans. The largest group is made up of fish, with a total of approximately 16,000 species. Necton is found at all depths and latitudes of the sea. Whales, penguins, seals are typical representatives of nekton in polar waters. The greatest variety of nekton can be found in tropical waters.

The most diverse life form and its economic value

This also includes the largest mammal on planet Earth, the blue whale, which grows up to 25-30 meters in length. These giants, as well as others, feed on plankton and micronecton. The largest representatives of nekton are whale sharks, which reach a length of 17 meters, as well as toothed whales (killer whales), great white sharks, tiger sharks, bluefin tuna and others.

Necton forms the basis of fisheries around the world. Anchovies, herring, sardines usually make up from one quarter to one third of the annual sea crop. Squids are also an economically valuable nekton. Halibut and cod are bottom fish, which have commercial value as food for humans. As a rule, they are mined in the waters of the continental shelf.

Benthos

What is the meaning of the word "benthos"? The term “bentos” comes from the Greek noun bentos and means “depths of the sea”. This concept is used in biology to refer to the community of organisms at the bottom of the sea, as well as fresh water bodies such as lakes, rivers and streams.

Benthic organisms can be classified according to size. Organisms larger than 1 millimeter are referred to macrobenthos. These are various gastropods, sea lilies, predatory sea stars and gastropods. Organisms with sizes from 0.1 to 1 mm are large microbes that dominate the bottom food chains, acting as a biogenic utilizer, primary producer and predator. Microbenthos category includes organisms smaller than 1 millimeter in size, these are diatoms, bacteria and ciliates. Not all benthic organisms live in sedimentary rocks, some communities live on rocky substrates.

There are three different types of benthos.

1. Infauna - organisms that live on the ocean floor, buried in the sand or hiding in shells. They have very limited mobility, live in sediment, are exposed the environment and have a fairly long life expectancy. These include sea shells and various shellfish.
2. Epifauna can live and move along the surface of the seabed to which they are attached. They live by attaching to stones or moving along the surface of sediments. These are sponges, oysters, snails, starfish and crabs.
3. Organisms that live on the bottom of the ocean, but can also swim in the water above it. This includes soft ones - pufferfish, flounder, using crustaceans and worms as a food source.

The relationship between the pelagic environment and benthos

Benthos are organisms that play a critical role in the marine biological community. Benthic species are a heterogeneous group, which is the main link in the food chain. They filter water in search of food, remove deposits and organic matter, thus purifying the water. At the bottom of the seas and oceans, unused organic matter settles, which are then processed by benthic organisms and returned to the water column. This process of mineralization of organic matter is an important source of nutrients and is crucial to ensure high primary production.

The concepts of pelagic and benthic environments are interconnected by many criteria. For example, pelagic plankton are an important source of food for animals living on soft or rocky ground. Anemones and sea ducks serve as a natural filter of the surrounding water. The formation of the pelagic environment at the bottom is also due to molting of crustaceans, metabolic products, and dead plankton. Over time, plankton forms marine deposits in the form of fossils, which are used to determine the age and origin of rocks.

Aquatic organisms are classified according to their habitat. Scientists believe that the habitat of these animals has a huge impact on their evolution. Moreover, most of them are well adapted to life in the specific environment that they inhabit. What is the main difference between the groups called plankton, benthos and nekton?

Plankton are microscopic or small animals compared to the other two types. Necton is a free-floating animal. What is benthos? It includes both freely moving, and those organisms that can not imagine their existence without the ocean floor. What about organisms that live mostly at the bottom, but can also swim - octopus, sawfish, flounder? Such life forms can be quite called nektobenthos.

The inhabitants of the aquatic environment - hydrobionts, inhabit almost the entire hydrosphere from its surface to maximum depths. A significant part of hydrobionts lives on the bottom or on another substrate - plants, underwater structures, ship bottoms, etc. These hydrobionts are called benthos. Bentos is divided into two large groups - zoobenthos and phytobenthos [Krylova, 1982]. Sometimes protozoal and bacterial benthos are also isolated, whose biomass in a number of reservoirs is quite large, despite the small size of the constituent organisms [Alimov, Finogenova, 1976].

Zoobenthos is an ecological group of organisms characterized by a bond with the bottom of water bodies as a substrate on which or inside which organisms spend their lives. Benthos organisms that have been in the water column for a long time belong to the group of planktonobenthos or bentoplankton [Zhadin, 1950].

Zoobenthos organisms are the largest group of hydrobionts, which is of great environmental and economic importance. They consume organic matter formed in water bodies and brought from outside, carry out self-cleaning of water bodies and streams, and form the basis of nutrition for most fish species. Finally, they can be used as human food, for pet food, and as industrial raw materials [Sveshnikov, 1989].

Traditionally, zoobenthos is divided into several groups depending on size - microbenthos (less than 0.1 mm), mesobenthos (0.1-2.0 mm) and macrobenthos (more than 2 mm) [Polyakov, 1994].

In a systematic way, freshwater macrozoobenthos consists of larvae of amphibiotic insects (chironomids and other dipterans, caddis flies, stoneflies, dragonflies, mayflies, coleopterans), crustaceans, oligochaetes, mollusks, leeches and some other animals. According to the method of nutrition, it contains phytophages, filtrators, predators, necrophages and saprophages, capable of carrying out a full cycle of the substance cycle [Rylov, 1930].

The vast majority of benthic invertebrate animals make up the group of so-called "food zoobenthos" directly used for food by fish. All these divisions are largely arbitrary. As studies have shown recent years, ciliates, other protozoa and even microorganisms in the composition of detritus can be consumed by fish - detritophages. The maximum sizes of fodder benthos are determined by the maximum sizes of fish living in water bodies - benthophages [Arabina, 1988].

Bentos is divided into epi and infauna. Representatives of the first live in the ground, the second - are introduced, buried in it. Among the bottom forms, colonial species are frequent, for example, sponges, and many intestinal ones.

According to their confinement to a certain soil, pelophilic forms that live in silt are distinguished, psammophilic - living in the sand, lithophilic - inhabiting stones, etc. [Zhadin, Gerd, 1961].

The nature of the soil, as well as the depth and topography of the bottom often have a decisive influence on the composition and abundance of bottom organisms.

Adaptations of bottom forms to life on the ground or in it come down to the development of means that resist demolition, the action of waves, falling asleep to a settling suspension. Attaching to the substrate, pulling the body up, deepening into the substrate, flattening the body, migrating bottom animals are the main ways to protect them from the adverse effects of the environment [Arabina, 1988].

Attachment to the substrate is characteristic of protozoa, sponges, some echinoderms, mollusks, gastrointestinal, algae and is achieved pneumatically, using root-shaped outgrowths, byssus - an adhesive secretion. It can be temporary (sea anemones, bivalves) or permanent (ascidia) [Rylov, 1930].

Deepening in the substrate is noted in some mollusks, echinoderms, and worms of insect larvae. Mollusks can penetrate into a tree or stone to a depth of 0.5 m. Hydrobionts living at the bottom of rivers adapt to life in a strong current due to hooks, suction cups, and claws [Krylova, 1982].

The following groups are distinguished with respect to the substrate in benthos:

Attached organisms (sessile benthos). An elongated body shape is usually characteristic. Often colonial organisms, such as sponges, bryozoans, corals. The organs of motion are reduced or change shape.

Lying organisms. They differ in a very extended and low body. Such organisms include crabs, bivalves, etc.

Entrapping organisms. Worms, holothurians, gastropods and bivalves, insect larvae, etc. The ability to bury is associated with morphological changes: a strong leg in bivalves and a loose shell, long siphons, powerful muscles of worms, etc.

Drilling organisms. In fresh waters, the larvae of some insects mine the leaves and stems of aquatic plants. Drilling organisms are essentially prisoners of their home, in which they make passages with the help of secreted acid or mechanically.

Freely moving organisms. Many animals move along the bottom with the help of variously arranged limbs [Kuzmina, 2007].

Thus, based on an analysis of the available literature, it can be concluded that zoobenthos is a large and diverse group of bottom invertebrates, which plays an important role in both marine and freshwater ecosystems.