5.1 Plankton Plankton (from the Greek planktos - soaring, wandering) is a set of pelagic organisms that do not have the ability for fast and active movements, but are passively transported by the current. Planktonic organisms cannot resist currents. Plankton includes mainly microscopic algae - phytoplankton, small animals – zooplankton and bacterioplankton. The plankton periodically includes the larvae of many animals floating in the water column. Phytoplankton inhabit layers of water with sufficient illumination, zooplankton and bacterioplankton inhabit the entire water column (Figure 5.1). Phytoplankton is of great importance in the life of water bodies, since it is the main producer of organic matter. Planktonic organisms are located either on the surface of the water, or in its thickness, or even in the bottom layer. To maintain a suspended state in water, plankton organisms have developed various adaptations: reduction of the skeleton (in some mollusks); soaking in water (scyphoid jellyfish); fatty inclusions (in cladocera and copepods); gas inclusions (in blue-green algae - gas vacuoles); increasing shape resistance - elongated along the axis (ribbon-shaped colonies of diatoms) or by forming outgrowths (ceratium from algae). Depending on body size, plankton organisms are divided into groups:
ultraplankton – sizes do not exceed several micrometers (bacteria);
nannoplankton (dwarf, small plankton) – body sizes are micrometers and dozens of them;
microplankton – tenths and hundredths of a millimeter;
mesoplankton - body length measured in millimeters (large representatives of phytoplankton, the main part of the zooplankton of the seas;
macroplankton - body length is centimeters;
megaloplankton - body sizes reach tens of centimeters.
Planktonic organisms are an important food component of many aquatic animals (including such giants as baleen whales, especially considering that they, and especially phytoplankton, are characterized by seasonal outbreaks of mass reproduction. ^ Figure 5.1 – Profile of the ocean and its inhabitants Prominent Ukrainian hydrobiologist Yu.P. Zaitsev identified a thin, several centimeters, layer in the planktonic film of life, calling it “the incubator of the sea.” The name “neustal” has been assigned to this specific pelagic biotope in the scientific literature. This author also discovered such an interesting phenomenon as “anti-rain of corpses”, caused by the floating of dead organisms for some time. Before they sink, they, being in the surface layer, manage to enrich it with organic matter, which during storms is churned into the well-known foam. Therefore, the base of the trophic pyramid in the surface film is made up of saprotrophic microorganisms: they process organic matter in excess. 5.2 Nekton Nekton (from the Greek nektos - floating) is a collection of pelagic actively moving animals that do not have a direct connection with the bottom, capable of resisting the force of the current and independently moving over considerable distances. These are mainly large animals that can overcome long distances and strong water currents. They are characterized by a streamlined body shape and well-developed organs of movement. Typical nektonic organisms are fish, squid, pinnipeds, and whales. In fresh waters, in addition to fish, nekton includes amphibians and actively moving insects. Many marine fish can move through the water at great speed. Some squid swim very fast, up to 45–50 km/h, sailfish reach speeds of up to 100–110 km/h, and swordfish reach speeds of up to 130 km/h. ^ 5.3 Plaiston and neuston Organisms that float passively on the surface of the water or lead a semi-submerged lifestyle are called plaiston (from Greek pleusis - swimming). They often use a surface tension film as a support or form air cavities and other floats. Typical pleistonic animals are siphonophores, some mollusks, etc. Plant organisms classified as pleistonic include sargassum algae and duckweed. Neuston is a unique type of plankton. Neuston (from the Greek neustos - floating) - a community of organisms living near the surface film of water. Organisms that live on top of the surface film - epineuston, below – hyponeuston. Neuston also includes the inhabitants of the upper five-centimeter layer of water. Neuston consists of some protozoa, unicellular algae, small pulmonate mollusks, water striders, whirligigs, mosquito larvae, etc. ^ 5.4 Benthos and periphyton Benthos (benthos - depth) - a set of organisms living at the bottom (on the ground and in the ground) of reservoirs. Benthos is divided into phytobenthos And zoobenthos. Mainly represented by attached or slowly moving animals, as well as burrowing animals. Only in shallow water does it consist of organisms that synthesize organic matter (producers), consume (consumers) and destroy (decomposers) it. At great depths, where light does not penetrate, phytobenthos (producers) is absent. Benthic organisms vary:
by way of life – mobile (wandering), slightly mobile (lying down) and immobile (attached);
by feeding method – photosynthetic, herbivorous, carnivorous, detritivorous;
by size - macro-, meso-, microbenthos.
The phytobenthos of the seas mainly includes algae. Flowering plants are also found along the coasts. The richest phytobenthos is in rocky and stony areas of the bottom. Along the coasts, kelp and fucus sometimes form a biomass of up to 30 kg per 1 m2. On soft soils, where plants cannot firmly attach, phytobenthos develops mainly in places protected from waves. Freshwater phytobenthos is represented by diatoms and green algae. Coastal plants are abundant, located inland from the shore in clearly defined belts. In the first zone, semi-submerged plants grow (reeds, reeds, cattails and sedges). The second zone is occupied by submerged plants with floating leaves (water lilies, water lilies, duckweeds). The third zone is dominated by submerged plants - pondweed, elodea, etc. All aquatic plants according to their lifestyle can be divided into two main ecological groups: hydrophytes– plants that are immersed in water only with their lower part and usually root in the ground, and hydatophytes- plants that are completely submerged in water, but sometimes float on the surface or have floating leaves. Benthic forms are most numerous in shallow waters. With depth, the number of benthos drops sharply. There is less zoobenthos in fresh water bodies than in seas and oceans. These are mainly protozoans, some sponges, ciliated and oligochaete worms, leeches, bryozoans, mollusks and insect larvae. Benthic organisms are divided into groups:
attached forms (sponges, corals, crinoids, representatives of mollusks, crustaceans);
lying organisms (scallops from bivalves, polychaetes from annelids, flat sea urchins from echinoderms);
burrowing organisms (peskozhil);
boring organisms (shipworm from bivalve mollusks);
freely moving organisms (crayfish, crabs, echinoderms, insect larvae, adult insects - water bugs, swimming beetles and water lovers).
A unique group of aquatic organisms is periphyton (from Greek peri - about and phyton - plant). This is a set of organisms that settle on underwater objects or plants and form so-called fouling on natural or artificial hard surfaces - stones, rocks, underwater parts of ships, piles, hydraulic structures (algae, barnacles, mollusks, bryozoans, sponges, etc.) . Periphyton organisms are fouling organisms. The morphological plasticity of aquatic organisms varies. They have less ecological plasticity than terrestrial ones, since water is a more stable environment and its abiotic factors undergo relatively minor fluctuations. Marine plants and animals are the least plastic. They are very sensitive to changes in water salinity and temperature. Freshwater animals and plants, as a rule, are much more plastic than marine ones, since freshwater as a living environment is more variable. The most flexible are the brackish-water inhabitants. They are adapted to both high concentrations of dissolved salts and significant desalination. However, there are a relatively small number of their species, since environmental factors undergo significant changes in brackish waters. Ecological plasticity serves as an important regulator of the dispersal of organisms. As a rule, aquatic organisms with high ecological plasticity are quite widespread.
Ecological plasticity of organisms (ecological valence) is the degree of adaptability of a species to changes in environmental factors. It is expressed by the range of values of environmental factors within which a given species maintains normal life activity. The wider the range, the greater the environmental plasticity. There are more stenobionts in the aquatic environment, since it is relatively stable in its properties and the amplitudes of fluctuations of individual factors are small
Stenobionts are opposed to ubiquists. They, unlike stenobionts, can exist in a wide variety of conditions.
Adaptive features of aquatic plants. Aquatic plants, unlike terrestrial ones, absorb moisture and mineral salts directly from the surrounding water, so their organization has its own characteristics. Their conductive tissues and root systems are poorly developed. Since the roots serve primarily for attachment to the submerged substrate, they lack root hairs. The powerful development of the root system in some of them - water lilies, egg capsules - ensures vegetative reproduction and storage of certain substances.
The main structural feature of hydrophytes is the presence of large intercellular spaces and cavities that create a special air tissue that ensures the buoyancy of the organs. Underwater hydrophytes differ from above-water ones in the absence of functioning stomata, thin dissected leaves, and poor development of mechanical tissues. Intense gas exchange with a lack of dissolved oxygen in the water is ensured either by very long and thin stems and leaves, the covers of which are easily permeable to oxygen, or by strong leaf segmentation.
A number of plants have developed heterophyly (various leaves). In water lilies and egg capsules, floating leaves are very different from submerged ones - their upper surface is dense and leathery, with a large number of stomata, which promotes better gas exchange with air; there are no stomata on the underside.
Due to the low water temperature, which negatively affects the reproductive organs, and the high density of the environment, which impedes the transfer of pollen, plants immersed in water reproduce vegetatively. However, many of them carry flowering stems into the air and reproduce sexually. Their pollen, fruits and seeds are carried by wind and surface currents. Coastal plants also use surface currents. Their fruits are highly buoyant and can remain viable for a long time while in water.
Adaptive features of aquatic animals. The adaptations of animals to the aquatic environment are more diverse than those of plants. Animals that live in the water column are characterized, first of all, by adaptations that increase their buoyancy and allow them to withstand the movement of water and currents. In small forms, a reduction of skeletal formations is observed. They have porous shells or hollow skeletal spines. Specific density of the body is reduced by the presence of water, air or fat in the tissues.
Animals passively swimming in the water column are also characterized by an increase in the specific surface area of the body. This is achieved by flattening the body, forming all kinds of spines and outgrowths.
Active swimming is carried out with the help of cilia, flagella, and also bending of the body. Jet swimming has become widespread due to the energy of the ejected stream of water. Thus, some squids reach speeds of 40–50 km/h. Larger animals have specialized limbs - fins, flippers. The body of such animals is covered with mucus and has a streamlined shape.
Freshwater animals use the surface film of water when moving. Whirling beetles and water strider bugs run freely across it. Their covers are not wetted by water, and their limbs have a special structure.
Bottom organisms, on the contrary, develop adaptations that reduce buoyancy and allow them to stay on the bottom even in fast-flowing waters. The heavy shells of the tridacna mollusk are well known, which lie freely at shallow depths and are held on reefs due to their mass.
Only in the aquatic environment are there animals that lead a sedentary lifestyle. The most famous of those attached to the ground are sponges, hydroid and coral polyps, sea lilies, bivalves, etc.
For aquatic animals, environmental pressure matters. Among the eurybates - living at both high and low pressure - holothurians are distinguished, living at depths from 100 to 9000 m. Among the stenobats - crinoids, pogonophora, living at depths from 3000 to 10,000 m. Deep-sea animals are characterized by poor development or absence calcareous skeleton, reduction of the organs of vision, increased development of tactile receptors, lack of body pigmentation or, conversely, dark coloring.
Compared to terrestrial communities, the biocenoses of aquatic organisms have some significant differences. The main one is the microscopic size of the vast majority of producers. Another characteristic feature is the presence of close interorganismal connections through the environment, in particular, the existence of various biochemical influences that play a crucial role in the organization of communities.
BENTHOS (from the Greek benthos - depth), a set of organisms living on the ground and in the soil of marine and continental reservoirs. Benthos is divided into plant (phytobenthos) and animal (zoobenthos). In zoobenthos, there are animals living in the soil - infauna (mainly many polychaete worms and bivalves, echiurids, sipunculids, some echinoderms, etc.), moving along the surface of the soil - onfauna (polychaete worms and mollusks, most echinoderms, various crustaceans) , attached to the substrate - epifauna (sponges, hydroids, sea anemones and various corals, bryozoans, sea acorns, some bivalves, etc.), as well as floating near the bottom and only periodically sinking to the bottom - nektobenthos (shrimps, mysids, some holothurians, bottom fish, etc.). By size, benthos organisms are divided into macrobenthos - 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 layer of soil) and microbenthos - less than 0.5 mm ( bacteria and other single-celled organisms). The basis of shallow-water phytobenthos in the seas are macrophytes (algae and sea grasses); Aggregations of benthic diatoms may also play a significant role. In the depths, in addition to animals, only bacteria and lower fungi live. The biomass of benthos in the seas decreases with depth: in the littoral and upper sublittoral zones - up to 5-10 kg/m2 and more, deeper in the sublittoral zone - hundreds and tens of g/m2, in the bathyal zone - grams, in the abyssal zone - usually not more than 1 g/m2, and in the central regions of the oceans, which are poor in life - 0.01 g/m2 or less. The share of shallow waters located near the continents (up to 200 m), occupying less than 8% of the ocean floor area, accounts for about 60% of the biomass of all oceanic benthos, and the share of the abyssal waters (deeper than 3000 m), occupying 3/4 of the bottom area, accounts for only less than 10 %. The total biomass of benthos in the ocean is estimated at 10-12 billion tons. In some areas of the eastern Pacific Ocean, at a depth of 2.5-3 km, so-called oases of life were discovered (in 1979) near outlets of hot underground waters (hydrotherms). In these areas, benthos biomass reaches several kg/m2; their fauna includes many previously unknown species of animals: giant bivalves and representatives of pogonophora. In fresh water bodies, benthos is qualitatively and quantitatively poorer than in sea water bodies. Animals it includes protozoa, sponges, roundworms, oligochaete worms, leeches, mollusks, crustaceans and the larvae of many aquatic insects. Phytobenthos is represented mainly by algae (especially blue-green and characeae) and various flowering plants (pondweed, water lilies, cattails, reeds and many others). Benthos serves as food for many fish, and in the seas also for some pinnipeds. Many species of shallow-water marine benthos are subject to fishing and aquaculture.
Benthos (Greek benthos - depth) are bottom hydrobionts. They can live on the surface of the soil and in its thickness, according to which the bottom population is divided into epi- and endobenthos. Based on size, micro-, meio- and macrobenthos organisms are distinguished. Microbenthos includes organisms less than 0.1 mm in size, meiobenthos - from 0.1 to 2 mm, macrobenthos - more than 2 mm. According to the method of feeding, representatives of zoobenthos are divided into carnivores (carnivores), herbivores, detritivores (feeding on organic particles), etc.
Benthic organisms are mainly attached or slowly moving animals (zoobenthos: foraminefera, sponges, coelenterates, worms, brachiopods, ascidians, sponges, corals, annelids, crustaceans, insect larvae, echinoderms, etc.), more numerous in shallow water. Common representatives of benthos also include bacteria, actinomycetes, fungi, and protozoa (especially rhizomes and ciliates). In shallow water, benthos also includes plants (phytobenthos: diatoms, green, brown, red algae, bacteria). At depths where there is no light, phytobenthos is absent. Some flowering plants are found along the coasts: zostera marina, rupee. Rocky areas of the bottom are richest in phytobenthos. In freshwater lakes, zoobenthos is less abundant and diverse than in the sea. It is formed by protozoa (ciliates, daphnia), leeches, mollusks, insect larvae, etc. The phytobenthos of lakes is formed by free-floating diatoms, green and blue-green algae; brown and red algae are absent. Taking root coastal plants in lakes form clearly defined zones, the species composition and appearance of which are consistent with the environmental conditions in the land-water boundary zone. In the water of continental fresh water bodies, near the shore, hydrophytes grow - plants semi-submerged in water (arrowhead, whitewing, reeds, cattails, sedges, trichaetes, reeds). They are replaced by hydatophytes - plants immersed in water, but with floating leaves (lotus, duckweed, egg capsules, chilim, takla) and - further - completely submerged (pondweed, elodea, hara). Hydatophytes also include plants floating on the surface (duckweed).
The ecological group of benthos also includes periphyton (peri - around, phyton - plant) - a set of fouling organisms that settle on various objects and the bodies of other organisms. The composition of periphyton includes not only plants, it can be sponges, bryozoans, barnacles (barnacles), bivalves and other invertebrates, which usually lead a sedentary or sedentary lifestyle. Periphyton organisms settle on the bottoms of ships, snags, logs and other floating objects, on plants and animals. In some cases, it is impossible to draw a clear boundary between benthos and periphyton, for example, in the case of fouling of rocks and various objects on the bottom.
Adaptations of aquatic organisms to the benthic and periphytic way of life primarily come down to the development of means of retention on a solid substrate, protection from falling asleep by settling suspended sediment, and the development of the most effective methods of movement. It is very typical for benthic and periphyton organisms to adapt to a temporary transition to a pelagic lifestyle at the larval stage, which provides these sedentary forms with the opportunity to disperse.
Retention on a solid substrate is achieved in various ways. Attachment to the substrate is observed in many plants, protozoa, sponges, coelenterates, worms, mollusks, crustaceans and other hydrobionts. Attachment can be temporary or permanent, and according to its mechanism - pneumatic (suction), in the form of continuous germination or root-like - using threads. Suction attachment is observed, for example, in Ancylus mollusks, leeches, and sea anemones. Continuous germination can be calcareous (corals), chitinous or horn-like (molluscs, barnacles). Attachment using roots and rhizoids is characteristic of higher plants and many algae (for example, kelp). Attachment by byssal threads is characteristic of a number of bivalve mollusks (mussel, zebra mussel).
Another form of retention is penetration into the substrate: partial or complete burying in the ground or penetration into hard rock by drilling and grinding. Many mollusks, echinoderms, worms, insect larvae and even some fish are capable of burrowing. For example, some sea eels dig a hole on the sandy bottom, where they hide in case of danger. Various crabs, shrimp, cephalopods, and fish (for example, flounder) have also adapted to temporarily burying themselves in the ground. Some sponges, mollusks, echinoderms, and crustaceans penetrate into solid substrates, destroying them mechanically or chemically (dissolution with acids).
As a protection against being covered by a layer of sediment, benthic organisms of different systematic groups converge to develop structures that are raised above the ground due to the appropriate body shape and stretching upward during the growth process. The most common body shape of attached benthic organisms is cone-shaped, funnel-shaped, mushroom-shaped, in all cases thinner below (sponges, solitary corals, mollusks). Sea lilies have a long stalk with which they attach to the ground, and glass sponges of the genus Euplectella look like an elongated tube. Along with stretching upward, protection from falling asleep in suspension in attached organisms is achieved by settling on substrates that rise above the bottom. Cirripedas, zebra mussels, and bryozoans grow on rocks and stones, various objects and organisms. Plants are saved from falling asleep by their rapid growth.
Based on the degree of mobility, benthic organisms are divided into vagrant (crabs, octopuses, starfish), weakly moving (molluscs, sea urchins) and attached (sponges, bryozoans, corals). In general, in this group the ability for active movements is less pronounced than in pelagic organisms. However, the low mobility of benthic and periphyton species in adulthood is usually compensated by the high mobility of their juveniles, leading a pelagic lifestyle. Many crustaceans and insect larvae migrate downstream of streams and rivers. To do this, they rise into the water column and, after swimming some distance, settle in a new place.
The most significant horizontal migrations in adulthood are performed by large crustaceans. The Kamchatka crab Paralithodes camtschtica moves to a distance of up to 200 km from the coast into the open sea in the fall, and in the spring it returns from its wintering grounds to coastal waters. Mass migrations of spiny lobsters Panularis argus occur in the fall with the onset of storms with a speed of 1 km/h and last for several days. When migrating, lobsters form chains of dozens of individuals, following strictly one after another, touching with their antennae the one in front.
In the seas, zoobenthos is represented mainly by foraminifera, sponges, coelenterates, nemerteans, polychaetes, sipunculids, bryozoans, brachiopods, mollusks, crustaceans, echinoderms, ascidians and fish (Fig. 3.23). The bulk of zoobenthos is confined to shallow water areas. In the littoral zone and in the upper horizon of the sublittoral zone, the mass of animal organisms in an area of 1 m2 can reach many tens of kilograms (mainly mollusks). At depths of up to 100-150 m, the benthos biomass is hundreds and tens of grams; at a depth of 500-1000 m, benthos biomass is also sometimes calculated in grams, deeper - in fractions of a gram, at greater depths (abyssal) - in milligrams. Vertical zoning is also observed in the distribution of benthos: 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. Of the marine plant organisms, the bulk of benthos in the seas consists of bacteria and algae (diatoms, green, brown and red). Some flowering plants are also common near the coasts: zostera, phyllospadix, ruppia, etc. The richest and most diverse phytobenthos is on rocky and rocky areas of the bottom, which serve as a durable substrate for the attachment of algae.
Rice. 3.23. Various representatives of marine benthos [Zenkevich, 1976].
Organisms that move freely along the bottom: 1 - crab Carcinus\2 - starfish Asterias;
3 - slope; 4 - flounder; 5 - mollusks - chiton (Chiton); 6 - scallop (Pecteri); 7 - saucer (Patella). Organisms attached to or lying on the bottom: 8 - oysters. Organisms that burrow into the ground: 9 - lancelet; 10-clam Mua. Rock-boring organisms: 11 - Pholas mollusk; 12 - crustacean - sea acorn (Balanus); 13 - ascidian Phallusia; 14- glass sponge Euplectella; 15 - tube worm Spirografis; 16 - Tabularia hydroid; 17- sea lily
Near the Murmansk, White Sea and Far Eastern coasts, algae from kelp and fucus (brown) often produce biomass from 15 to 30 kg per 1 m2 of the bottom in the littoral zone and the upper horizon of the sublittoral zone. Thickets of red algae Phyllophora are known in the northwestern part of the Black Sea at a depth of 20-60 m, where its mass averages 1.7 kg per 1 m2 of the bottom, and in general - millions of tons. On soft soils, phytobenthos develops only in shallow water 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 unequal absorption of rays of different wavelengths; In the upper horizon, green algae are usually concentrated, below - brown, and even lower - predominantly red.
A significant part of marine benthos is eaten or used as technical raw materials. Animals include mollusks (oyster, mussel, etc.) and crustaceans (crabs, shrimp, lobsters, etc.). Of the 1.2 million tons of marine invertebrates harvested annually, 62% are mollusks and 30% are crustaceans. Many mollusks have food value for fish and, in addition, produce mother-of-pearl and pearls. Among other benthic animals, sponges and noble coral are of commercial importance.
Some sea bottom animals are harmful. First of all, these are marine woodworms - teredinid bivalve mollusks. Many marine organisms settle in large numbers on the bottom of ships, reducing the speed of the ships. Marine benthos plants are used as food and technical raw materials: kelp, ulva, porphyry, ahnfeltia, phyllophora and zoster.
The composition of benthos in fresh continental water bodies is also quite diverse (Fig. 3.24), but to a lesser extent than sea benthos. However, lakes and rivers are inhabited by numerous species of insects and their larvae, while in the marine environment insect species are rare. 
Rice. 3.24. Representatives of benthos of continental freshwater bodies.
1 - cattail (Typha); 2 - lake reed (Scirpus)\ 3 - arrowhead (Sagittaria);
4- water lily (Nymphaea)\ 5, b-rdest (Potamogeton); 7-chara algae (Chara);
8 - pond snail (Ytpaea); 9- water mite (Hydracarina); 10 - amphipod crustacean (Gammarus); 11 - isopod crustacean water donkey (Asellus); 12 - mosquito larva (Culexpipiens); 13 - mayfly larva (Cloeon); 14 - mayfly larva (Caenis); 15 - water diving beetle (Dytiscus); 16-water scorpion (Ronatra)\ 17-water smoothie bug (Notonecta);
18 - dragonfly larva (Lestes)
Some plants that are part of freshwater benthos, such as reeds, reeds, etc., are used in industry and agriculture. An increase in the amount of freshwater phytobenthos sometimes turns out to be harmful and leads to overgrowing of the pool; The means of control is mowing. However, a green belt of submerged plants along the shore of a river or lake can serve as an effective biological filter - a barrier for a water body that can consume excess organic substances and prevent their penetration into the water column.
Many aquatic organisms have adapted to existence at the interface between water and soil. Representatives of pelagobenthos live in the zone of contact of the water column with the bottom, either swimming, moving along the ground or burrowing into it. Depending on their size and degree of mobility, representatives of pelagobenthos belong to nekto- or planktobenthos. Among the representatives of nektobenthos, the most common are higher crayfish and fish. Typical planktobentonts include transparent larvae of the Chaoborus mosquito living alternately in water and soil, many beetles, copepods and cladocerans, a number of rotifers equipped with a leg, numerous chlorococcal, desmidian and blue-green algae.
It should be noted that quite often the rigid assignment of aquatic organisms to one or another ecological group based on their habitat is conditional. The same species at different stages of ontogenesis can be included in different ecological groups. For example, typical benthic animals such as crabs, starfish and mollusks have larvae that lead a planktonic lifestyle for some time (Fig. 3.24).
In general, the life forms of aquatic organisms can be very diverse. In this case, one should always take into account the breadth of adaptation spectra of organisms. There are approaches to classifying aquatic inhabitants based on their feeding methods, relationship to salinity, pressure, and temperature. It is also possible to classify aquatic animals according to their modes of movement. For example, the ecological group of species that move in water in a reactive manner includes such heterogeneous representatives in systematic position as jellyfish, cephalopods, some ciliates and flagellates, the larvae of some dragonflies, etc. (Fig. 3.25). 
Rice. 3.25. Representatives of an ecological group of organisms that move in water in a reactive manner.
1 - jellyfish Cytaeis vulgarus; 2 - pelagic holothurian Pelagothuria;
3 - larva of the rocker dragonfly; 4 - swimming octopus Octopus vulgaris
- (from the Greek benthos depth), benthic organisms, a set of organisms living at the bottom of reservoirs, adapted to the corresponding substrate (litho, psammo, pelo, argillo, phytophilic species). Benthos is divided into plant (phytobenthos), ... ... Ecological dictionary
- (from the Greek benthos depth) a set of organisms living on the ground and in the soil of the bottom of reservoirs. Marine 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 the Greek benthos depth), a set of organisms living on the ground and in the soil of marine and continental reservoirs. B. is divided into plant (phytobenthos) and animal (zoobenthos). In zoobenthos, animals that live in the depth of the soil are distinguished... ... Biological encyclopedic dictionary
BENTHOS, flora and fauna of the benthic or bottom areas of the sea. The fauna includes immobile forms such as sponges, crabs and snails that move freely along the bottom, as well as burrowers such as worms, as well as countless... ... Scientific and technical encyclopedic dictionary
A set of organisms living on the ground and in the ground of water bodies. (Source: “Microbiology: a dictionary of terms”, Firsov N.N., M: Drofa, 2006) ... Dictionary of microbiology
Exist., number of synonyms: 7 macrobenthos (1) mesobenthos (1) microbenthos (1) ... Synonym dictionary
Organisms that inhabit the bottom of a reservoir. There are halobenthos, inhabiting the bottom of the sea, and limnobenthos, inhabiting the bottom of fresh water bodies. Depending on the lifestyle of animals, B. can be sessile and mobile. Geological Dictionary: in 2 volumes. M.: Nedra... Geological encyclopedia
Benthos- a set of macroorganisms living at the bottom of reservoirs... Source: MU 1.2.2743 10. 1.2. Hygiene, toxicology, sanitation. Procedure for sampling for detection and identification of nanomaterials in water bodies. Guidelines (approved... ... Official terminology
A collection 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); *detritivores, eating the remains of dead animals and... ... Dictionary 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, shores and various underwater objects. KB. relate as forms motionless... ... Great 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 of the sea exogenous ... Technical Translator's Guide
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 using the example of biogeography and ecology of marine benthos. The main aspects of biology are considered... eBook
- Benthos of salmon rivers of the Urals and Timan, V. Shubina. The monograph summarizes the results of long-term (1958-2004) hydrobiological studies conducted on watercourses flowing from the Timan Ridge and the western slope of the Ural Mountains and ...
Typical representatives of macrozoobenthos
Benthos species
“Benthos” means “depth” in Greek. This name includes organisms that live on the ground and in the soil of the bottom of rivers, seas and oceans.
Benthos is divided into animal (zoobenthos) and plant (phytobenthos). In zoobenthos there are animals living in the ground and on the ground, mobile, sedentary and immobile, partially embedded in the ground or attached to it. According to their feeding method, they are divided into carnivores, herbivores, and those that feed on organic particles.
Among benthic animals there are large, medium and small. Organisms that move freely along the bottom include starfish and crabs. There are organisms that either float up or lie on the bottom - flounder, stingrays. There are also very sedentary ones - chiton mollusks, scallops, limpets. Oysters and other shellfish are attached to the bottom, and lancelets are buried in the soil. The bulk of zoobenthos lives in shallow areas of the seas. Plant benthos is mainly algae. Benthos serves as food for many fish and other aquatic animals, and is also used by humans (for example, oysters, some fish). An example of benthic animals is , methiola, miya, and many others.
Also distinguished are epibenthos, organisms that live on the surface layer of bottom sediments, and endofauna (), organisms that live directly inside the bottom sediment. Epibenthos can be immobile (sessile) or moving (vaginal).
Based on the method of obtaining food, the following types of benthic organisms are distinguished:
- Suspension eaters
- Groundeaters
- Scrapers
- Filters.
Benthos is classified by size into:
- , > 1 mm;
- , < 1 мм и >32 µm;
- , < 32 мкм.
see also
Literature
Benthos:
- Benthos // Biological encyclopedic dictionary / chapter. ed. M. S. Gilyarov. - M.: Soviet Encyclopedia, 1986. - P. 56.
- Benthos / L. A. Zenkevich, T. F. Shchapova //: [in 30 volumes] / ch. ed.