Order Diverse crustaceans, or amphipods (Amphipoda). Gammarus or amphipod crustacean - universal food (Description, species, harvesting, breeding, feeding) What is the name of the amphipod crustacean

Amphipods are well known not only by zoologists, but by all fishermen. In different parts of the USSR, local residents call them differently: “stonoga” in the Caspian Sea, “mormysh” or “mormyshka” in the Urals and Western Siberia, “barmash” in Baikal and Eastern Siberia. On Baikal, there is an under-ice winter fishing for omul - “barmashenye”: amphipods from the surrounding lakes are brought alive in barrels to Baikal, they break holes in the ice and throw handfuls of crustaceans there, thus attracting omul, which is caught by hooking. The feeding value of amphipods for fish is widely known. They serve as excellent bait for anglers. Fish farmers transport them together with mysids to newly created reservoirs to improve the conditions for fattening fish. Attempts were made to artificially breed these crustaceans in hatcheries. Under natural conditions, many fish use amphipods as food, and some, such as trout, feed exclusively on them. Along with this, it is also well known that amphipods in some cases damage fishing nets and eat fish caught in them.

In their structure, they are in many ways similar to isopods, but their body is often compressed from the sides, and not from top to bottom, as in isopods. However, among the amphipods there are species with a flattened dorsal-abdominal direction, as well as with a cylindrical body. The head, as in isopods, fuses with the first, occasionally with the first two thoracic segments, and the carapace is absent. The eyes are sessile and located on the sides of the head. In the pelagic Phronima, each eye is divided into two, and in the family Ampeliscidae even into 3 parts (Tables 34, 12). On the other hand, in Oedicerotidae, both eyes on the dorsal side are connected so that one huge unpaired eye is formed. Deep-sea and subterranean species are, as usual, blind, but some of them have dark, faceless "eye spots" in place of eyes, the purpose of which remains unknown. Under the covers of the head, near its dorsal side, many amphipods have a pair of statocysts, with 1-3 statoliths in each. Both pairs of antennae are usually long and equipped with sensitive cylinders and bristles. Mouth appendages of chewing type.

In all amphipods, the epipodites of the thoracic peduncles, with the exception of the legs of the first pair, and sometimes of some others, are transformed into leaf-shaped thin-walled gills. In many cases, the gills are folded, which increases their respiratory surface, and sometimes they are equipped with finger-like outgrowths. Since breathing is carried out by the appendages of the thoracic legs, the heart is entirely placed in the thoracic region. In mature females, plates of the brood pouch are attached to some of the pectoral legs on the inside of the gills. Unlike isopods, cums, and others, the brood pouch of amphipods does not disappear after the end of each breeding season.

The abdominal region consists of 6 segments. Usually it is somewhat shorter than the chest, but has the same width. However, in many planktonic amphipods, it is narrowed, due to which the whole body acquires a teardrop shape (Fig. 255, 1). The limbs of the three anterior abdominal segments are adapted for swimming. Their branches are multisegmented and equipped with numerous swimming bristles. The limbs of the three posterior abdominal segments are directed backwards, and their branches are not dissected (with the exception of the external branches of the last pair, which often consists of 2 segments). These are jumping legs, or uropods. In representatives of the suborder Laemodipodea, which combines sea goats and whale lice, the abdominal region is very shortened and lacks segmentation, and the abdominal legs are reduced and often absent altogether. In the suborder Ingolfiellidea, which is poor in species, the swimming legs are turned into small undivided plates. The abdominal section is followed by a short telson, which has the shape of a triangle, an oval, or a notch split into two lobes.

The body covers of amphipods are often smooth, but in many cases they are armed with various keels, teeth and spines. Such a sculpture of the covers sometimes has a protective value. Among the numerous amphipods of Baikal, some are smooth, and some are “armed”. In the intestines of Baikal gobies, which feed mainly on amphipods, smooth species sharply predominate. Obviously, the "armed" are to some extent protected from the attack of bulls.

Amphipods, as a rule, are colored rather uniformly in brownish, greenish and yellowish tones. The exception is the Baikal species, among which there are variegated, blue, red, green (Table 34, 1, 4, 5, 7). Deep-water and underground species are colorless, but among the planktonic deep-sea species there are also red ones, such as Cyphocaris (Tables 34, 13), Paracyphocaris and a number of related genera.

The greenish coloration of freshwater Gammarus is caused by carotenoids produced from carotenes contained in the plants eaten by the crustacean. In the aquarium, representatives of the pigmentless underground race Gammarus were kept for a long time in complete darkness and under conditions of constant illumination. Regardless of this, they acquired a normal greenish color if they received plants as food. However, there are also hereditary factors that determine color. Occasionally, along with greenish ones, red specimens of amphipods are found. Experiments on crossing them with each other and with normal individuals showed that the coloration depends on three pairs of genes, with the greenish color gene dominant.

In accordance with the different structure of the legs, the movements of heteropods are very diverse. Most of these crustaceans can crawl along the bottom and plants, moving with their thoracic legs, swim with the help of the anterior ventral legs, and jump, pushing off the substrate with the hind ventral legs. It should be borne in mind that the name of the entire detachment "amphibians" is inaccurate. Only in very shallow streams or at the very shore of a reservoir do crustaceans really swim on their side, and where the depth allows it, they swim with their backs up, but often lie on the ground on their side. However, since they are easiest to notice at the most insignificant depth, a deliberately incorrect name was established behind them.

Most amphipods move in all three ways mentioned, switching from one to the other depending on the circumstances. Even sea goats, despite the absence of swimming abdominal and middle thoracic legs, can not only crawl on algae and hydroids, but also swim by bending their body. The semi-terrestrial Talitridae are excellent at jumping distances of up to 30 cm and even more. But along with such benthic, benthic and semi-land dwellers, there are real planktonic amphipods that swim all their lives. These are, firstly, all the numerous species of the suborder Hyperiidea and, secondly, individual representatives of the most extensive suborder of amphipods - Gammaridea.

Planktonic amphipods are characterized by very thin, often transparent covers and the presence of fatty inclusions in the body, which reduces their specific gravity and facilitates soaring in the water. In Hyperiidea, the body is usually drop-shaped, due to the fact that its front part is wide, swollen, and the back is narrowed. Interestingly, one also planktonic, but completely unrelated family, Hyperiopsidae, belonging to the suborder Gammaridea, has a very similar body structure. Probably, with this shape, the resistance of water when the crustacean moves forward is minimal. In some hyperiids, the body, on the contrary, is thin, arrow-shaped (Fig. 255, 2). Usually, planktonic amphipods have strongly developed swimming legs, and jumping ones act as depth rudders. Shallow and semi-deep-water Hyperiidea almost always have enlarged eyes, which can cover the entire or almost the entire head. Direct observations of the functions of these huge eyes have not been made, but it can be assumed that with their help the crustaceans find their prey. In addition, the eyes are of no small importance during diurnal vertical migrations, which are very characteristic of shallow-water hyperiids. All planktonic amphipods, with one exception, live in the sea and do not tolerate desalination at all. The only freshwater plankton representative of this order - Macrohectopus branickii - lives in Baikal.

Bottom amphipods often also swim for quite a long time. Thus, for example, sexually mature males of Pontoporeia affinis, which is widespread in the lakes of the northern part of Europe and America, in desalinated areas of the Baltic Sea and in the Caspian Sea, differ from females in their elongated posterior antennae and spend most of their lives in the water column looking for females crawling along the bottom. Some benthic species (Bathyporeia, Cogophium) leave the bottom at night and rise to the surface of the water.

Many amphipods willingly and quickly burrow into the ground. Usually they stick their rear and sometimes front antennas into the ground and begin to rake it with their pectoral legs, discarding soil particles with their prehensile front legs. Sometimes this happens very quickly. On the sandy coasts of the Azov and the middle and southern parts of the Caspian Sea, one can observe how each incoming wave brings masses of amphipod Niphargoides (Pontogammarus) maeoticus ashore. When it starts to retreat, the crustaceans burrow into the ground until the next wave appears, forcing them to crawl out of the ground, and then it repeats all over again. The ability to burrow into the ground makes it easier for some Ponto-Caspian species to spread up rivers, as the crustaceans can thus resist the current and not drift down. For example, Niphargoides (Pontogammarus) sarsi inhabit the entire Volga up to its upper reaches, burrowing into the sandy soil of the river.

Other species dig real holes in the ground, and some build tubes or other forms of shelter from the ground. Some species of the underground amphipod Niphargus dig quite complex tunnels in the soft soil of underground lakes with several entrances and with extensions - "living chambers". Representatives of many families of the Gammaridea suborder poison (Ampel iscidae, Corophiidae, Aoridae, Amphithoidae, Photidae, etc.) have unicellular glands located in the middle segments of the hind pectoral legs or in the lateral plates of the thoracic region and opening in the claws of the pectoral legs. These glands produce a secret, with the help of which the crustaceans, when building pipes and houses, fasten soil particles, scraps of algae, etc.

All Corophiidae live in tubes they have built. Corophium volutator cements the walls of the tunnel 4-8 cm long that it pulls out with a secret, and before the onset of winter it deepens the tunnel up to 20 cm. C. curvispinum attaches its tubes to the surface of the soil, stones, mollusk shells, as well as to the bottoms of ships. Thanks to its houses attached to the ships, this Caspian species spread very widely: the ships took it all over the Volga and other Russian rivers, it penetrated into the Baltic Sea basin and even into England. During the construction of shelters, corophiids use elongated posterior antennae, with which they capture suitable building material (Fig. 257).

Mass marine Ampel iscidae build small thin-walled sac-like houses from sand or silt, containing only the body of the crayfish, and its head with antennas sticks out. Leptocheirus constructs from soil particles or scraps of plants something like a dome over a branch of a hydroid or algae, which serves as a kind of floor for its dwelling. Microdeutopus, Microprotopus, and others of the same material, sometimes with the addition of their own excrement, make tubes with inlet and outlet. In this case, inside the tube, they have to repeatedly turn around their own axis, since the cement glands, as already mentioned, open in the claws of the pectoral legs, and the crustacean can cement some part of the passage, being turned towards it only by the ventral side of the body.

Bottom amphipods, which do not burrow into the ground and do not make holes or houses, usually hide among algae, thickets of hydroids and sponges or under stones, in rock crevices, etc. animals only as a place of settlement. Sea goats crawl along algae and branches of hydroids and, holding on to them with three pairs of hind pectoral legs, raise the rest of the body so as to be able to grab animals passing by with grasping front legs. Their hunting posture resembles the corresponding position of the body of the isopods Astacilla (Fig. 246).

Most amphipods can be considered omnivores, which means that they are able to use organic matter in various forms. Freshwater and many marine amphipods eat plants, both living and dead, soil, carcasses and remains of animals, and, on occasion, small living animals. They bite off pieces of food with their mandibles and grind them, and the jaws retain small particles, preventing them from falling out of the scope of the oral appendages. Some species can also obtain food by filtration. The massive amphipod of the coasts of the Caspian and Azov Seas - Niphargoides maeoticus - passively filters the suspension brought by the waves. When the wave begins to move away from the shore, the crustaceans sit in the ground, sticking out the front end of the body from it, when the ground is exposed, they burrow into it entirely.

Filtration is the main way of obtaining food for Leptocheirus, Corophiidae and Ampeliscidae. These animals, sitting in their houses, excite a strong current of water by sweeping the anterior ventral legs, passing water through a dense network of setae located on the anterior thoracic legs. At the same time, Corophiidae stir up the surface layer of soil with elongated rear antennae. Diatoms, bacteria and small plant remains are digested by crustaceans. Other species, such as many members of the Haustoriidae family, scrape off algal and bacterial growth from soil particles. Chelura terebrans, like limnoria and spheroma, sharpens wood and probably feeds on sawdust.

The inhabitants of groundwater swallow the soil, which is always found in their digestive tract. However, long-term observations of Niphargus orcinus virei have shown that the organic matter contained in the soil cannot fully ensure all the vital functions of the crustacean, in particular its growth and reproduction, but only supports its existence. From time to time, the remains of plants and animals are brought into underground reservoirs, and only such more nutritious food allows nifargus to grow and multiply. This is connected with the structure of the oral appendages of nifargus, which retain the character of chewers. The bottom amphipod of our northern seas Anonyx nugax feeds mainly at night. The intensity of its nutrition is also different in different seasons: it increases in autumn and winter and falls in spring and summer.

All amphipods have separate sexes. Sexual dimorphism is often well expressed, but in different ways in different families and genera. In representatives of the Gammaridae family, males are usually larger than females, but in representatives of the Lysianassidae family, inverse size ratios are observed. In some Baikal amphipods belonging to the Gammaridae family, males are so much smaller than females that they are called dwarf. They reach sexual maturity much earlier than females, after which their growth stops. For example, the length of mature males of the planktonic Macrohectopus branickii does not exceed 5.5 mm, while the length of mature females varies between 14 and 30 mm. In males of many Gammaridae and all Talitridae, the claws of the anterior pectoral legs are more strongly developed than in females. Often males have longer antennae with more numerous sensory organs on them. In many species of the subterranean genus Niphargus, males differ sharply from females in the elongated terminal segment of the outer branch of the posterior uropods, and sometimes, in addition, in the elongated branches of one or two pairs of anterior uropods. Sexually mature females always have a brood pouch.

Recent studies have shown that the development of male secondary sexual characteristics in amphipods is determined by the hormone of special endocrine glands, the so-called androgenic glands, which lie along the seminal ducts, but are not connected with them. This hormone is released into the blood. Transplantation of androgenic glands to young females of Orchestia gammarella led to the development of the prehensile legs characteristic of males and even to the degeneration of their ovaries into testes. In some cases, sex determination depends on external conditions, in particular temperature. In the brackish amphipod Gammarus duebeni, when eggs mature at temperatures below 5°C, males emerge from them, and at temperatures above 6°C, females. Due to this, all crustaceans born in winter turn out to be males, and females are born only in spring.

Mating usually lasts for several days. The male is located on the dorsal side of the female, holding with his claws the anterior edge of her first and the posterior edge of her fifth free thoracic segment and waiting for her molting. After the female molts, the male moves under her ventral side, folds his anterior abdominal legs together, inserts them several times between the posterior plates of her brood pouch, and at the same time releases sperm from his genital openings. With the help of the anterior abdominal legs, the sperm is transferred to the pouch, where after 1/2-4 hours (in Gammarus) eggs are laid, which are fertilized here.

Normal oviposition can only occur when there is sperm in the brood pouch. In experiments with Gammarus duebeni, it was possible to clog the genital openings of males. After mating with such males, which occurred normally, except for the fact that they did not secrete sperm, half of the females did not lay eggs at all, and the rest did not completely lay them, in small numbers.

The number of eggs laid by amphipod females varies in different species and, moreover, within each species is determined by the size of the female. Usually it ranges from 4 to 100, occasionally, for example, in Gammarus oceanicus, it reaches 177. At the same time, the fecundity of species that breed several times during the year decreases towards the end of summer and autumn. In some amphipods, in different parts of their area of ​​​​distribution, fertility turns out to be different: in the north it is greater than in the south. Some Caspian species are very prolific (Amathillina spinosa - up to 251, Niphargoides robustoides - up to 239, Gammaracanthus loricatus caspius - up to 336 eggs). High fecundity has been recorded in the Antarctic Chevreuxiella obensis. The only female of this species caught so far contained 344 embryos in the brood pouch. However, the fecundity of large (46 mm) females of the White Sea Anonyx nugax, bearing up to 950 embryos, is even higher.

The amphipod embryos, which are still in the egg membranes, are curved to the ventral side, which distinguishes them from the embryos of other peracarids, which, on the contrary, are curved to the dorsal side. Another important difference between amphipods and most orders close to them should be considered the presence of all thoracic limbs in young crustaceans that hatched from eggs. Thus, amphipods do not have a semolina stage.

Young crustaceans usually leave the mother's pouch in 20-30 days. The duration of the incubation period depends on the temperature. So, for example, off the coast of England, juveniles of Gammarus obtusatus remain in the mother's pouch for 12-14 days, and in the White Sea for at least 21 days. The cave Niphargus orcinus virei, living at a constant temperature of about 11 ° C, has an incubation period of 254-3 months.

Young crustaceans emerging from the brood pouch grow quite quickly and evenly, periodically shedding. Before reaching sexual maturity, juveniles of Gammarus and Niphargus must molt 13 times, but in different species and at different temperatures this takes a different time. In the Baikal lakes, G. lacustris reaches sexual maturity 3 months after emerging from the brood pouch; in the lakes of Western Siberia and Lake Sevan, the same species becomes sexually mature the next year after birth, and Niphargus orcinus virei - only after 2 1/2 years.

The breeding season of amphipods is usually very long and falls on the warmest time of the year. For example, in the South Caspian, for most species, it begins in February-March and ends in September-October; in the White Sea, littoral species of Gammarus (except for G. setosus) breed in June-August. The common freshwater G. lacustris starts breeding in April-May and finishes breeding by late summer or autumn (depending on temperature).

Amphipods of the genus Anisogammarus from the littoral of the Kuril Islands bear eggs and juveniles throughout the winter, but young crustaceans leave the brood pouch only in spring or summer, when the temperature reaches a certain value, which is different for different species. In two species, juveniles are released at 2-4°C, in four species, at 4-8°C, and in one, at 7-10°C. If the habitat temperature remains more or less constant, amphipod breeding can continue throughout the year. In the streams and springs of Germany, G. pulex breeds from January to October. However, for the caveman Niphargus orcinus virei, despite the constancy of the temperature of its habitat, a periodicity in its reproduction was noted, which cannot be associated with environmental factors. On the other hand, intertidal amphipods of the North Atlantic - G. zaddachi and probably G. finmarchicus - experience significant temperature fluctuations, but nevertheless breed all year round. During the breeding season, each female gives from two to 5-6 litters. Since some of the young crustaceans have time to reach sexual maturity in the same season and, in turn, give offspring, the number of amphipods can increase very quickly. Their life expectancy is usually 1 to 2 years, but Niphargus orcinus virei lives on average 6 years, sometimes reaching 30 years.

The vast majority of amphipods inhabit marine water bodies, in which these crustaceans are widespread and very numerous everywhere. Within the tidal zone, and in many cases even at some distance from the strip covered by the maximum low tide, semi-land "sea fleas" - amphipods from the Talitridae family live. They got their name due to the fact that on land they often jump, pushing off the surface of the ground with their belly and uropods. During the day, sea fleas burrow into the sand, hide under rocks or algae, etc., and at night they actively move along beaches and other coasts, looking for dead algae that they feed on. They breathe with gills and can only exist in a sufficiently humid atmosphere. Under the experimental conditions, sea fleas survive underwater for some time, but always try to get out onto land.

On the Commander Islands, they hibernate high above sea level, under a thick layer of snow, falling into suspended animation. On the Shantar Islands, with the onset of frost, sea fleas migrate from the coast to the forests and sometimes climb into the attics of houses, and return to the sea in spring.

Their ability to navigate by the sun is remarkable. The Italian researchers Papi and Pardi made the following experiment: they took a round mold and divided it into 16 sectors with radial strips. This simple device was equipped with a magnetic needle. Hundreds of amphipods were placed in the center of the circle. After some time, the vast majority of crustaceans gathered in the sector facing the sea. It turned out that at every hour of the day, crustaceans move at a certain angle to the sun (and at night, to the moon). In the dark, they are unable to navigate. At the same time, crustaceans living in different parts of the coast are adapted to orientation with respect to the sun at different angles, depending on the direction of the coast. This amazing ability does not depend on external conditions such as temperature. Regular changes in the angle between the light source and the direction of movement of the animal during the day can be considered one of the best examples of the existence of the so-called "biological clock", i.e. regular daily changes in the characteristics of the organism, controlled by internal factors.

Several species of Gammarus and Anisogammarus can be considered common inhabitants of the tidal zone of our northern and Far Eastern seas. At low tide, they hide among the algae or under stones, and at high tide they move briskly in search of food. Some of them can withstand significant or even complete desalination well. In the littoral of our northern seas, there are often several thousand individuals of these crustaceans per 1 m2.

The amphipod fauna of the continental slope is the richest and most diverse. About 260 species live here in the Barents Sea, 250 species in the Sea of ​​Japan. Some of the amphipod species of the continental slope are found in large numbers. In the Chukchi Sea, there are up to 24 thousand Pontoporeia specimens and up to 14 thousand Lembos specimens per 1 m2 of the bottom. A trawl in this sea brought such a mass of amphipods that, poured onto the deck, they formed swarming heaps up to half a meter high.

With depth, the species diversity and number of amphipods decrease, however, even from great ocean depths, more than 6000 m, about 300 species are currently known. Most of them belong to widespread genera that are also found at shallower depths, but among them there are also very peculiar representatives. Thus, for example, the pelagic amphipod Vitjaziana gurjanovae lives in the Kuril-Kamchatka depression, which is classified as a separate family and does not ascend to depths of less than 6000 m.

Fresh waters are inhabited by a relatively small number of amphipod species. In the northern hemisphere, the lacustrine amphipod Gammarus lacustris is extremely widespread, living in a wide variety of lakes, often in huge numbers. It can exist in both fresh and highly mineralized water bodies and endure various adverse conditions, including a winter decrease in the oxygen content in the water. When the winter freeze sets in, masses of crustaceans accumulate under the lower surface of the ice. In Siberia, amphipods are harvested by punching holes in the ice and catching its lower surface in various ways. Other species of the same genus live in flowing waters - G. pulex, G. balcanicus, etc.

The amphipod fauna of Lake Baikal, consisting of 240 species, is unusually rich and unique. They live on the bottom or near the bottom, from the water's edge to the extreme depths, that is, up to 1620 le, and only one species - Macrohectopus branickii - leads a plankton lifestyle. Different species are confined to different depths and soils. Many of them are equipped with keels, spikes or bumps, giving them a very bizarre appearance. It is believed that all these species originated in Baikal from a few initial ancestors in a relatively short geological time. Only 52 species penetrate from Baikal into the Angara flowing from it, and about 20 of them spread further along the Yenisei to the Yenisei Bay. After the creation of the Irkutsk reservoir on the Angara, the number of Baikal amphipods in the new reservoir decreased, and some species disappeared altogether.

Amphipods of marine origin live in the rivers flowing into the Caspian, Black and Azov Seas, which also live in the Caspian Sea itself and in the desalinated parts of the Azov-Black Sea basin. Some of them go high upstream, for example along the Volga to Yaroslavl, where Dikerogammarus haemobaphes, Corophium curvispinum and Niphargoides sarsi are found. Even higher they go along the Oka and Kama, moving 3200 km from the sea. Sometimes in rivers they develop in very large numbers. In the lower reaches of the Oka, there are up to 168 thousand Corophium specimens per 1 m2 of the bottom.

One of the amphipods of Caspian origin - Gammarus ischnus - penetrated from the Ponto-Caspian basin to the Vistula, which belongs to the Baltic Sea basin, and Corophium curvispinum spread even more widely due to the ability to attach its houses to the bottoms of ships.

It is remarkable that amphipods of Caspian origin, invading rivers, displace ancient freshwater species, almost never meeting with them. The same antagonistic relationships have also been noted for some other species and genera of heteropods. In England, Gammarus pulex displaces G. duebeni; in Moldavia, G. balcanicus and G. kischineffensis also exclude each other. water.

It is not yet clear how this displacement is carried out. In an aquarium, some of the antagonistic species live peacefully together. Only in one case was it possible to elucidate the mechanism of displacement of one species, namely G. duebeni, by another - G. salinus. It turned out that G. salinus males readily mate with G. duebeni females, while G. duebeni males mate only with females of their own species. After mating with a male of another species, G. duebeni females lay unfertilized, incapable of developing eggs. Due to this, in places of contact between both species, the abundance of G. duebeni is constantly decreasing.

Amphipods are common not only in surface water bodies, but also in groundwater. In the caves, wells and springs of Western Europe, the Caucasus and Western Ukraine lives a very species-rich genus Niphargus. In the underground rivers and streams of Transcaucasia, a special genus Zenkevitchia, which is widespread only there, is found. Representatives of the genera Crangonyx and Synurella are found in separate groundwater outlets over a vast area of ​​the entire northern hemisphere. Among the other numerous underground amphipods, representatives of the suborder Ingolfiellidea are of particular interest from the point of view of their distribution. Currently, only 11 species of this suborder are known. Of these, 7 live in the underground fresh waters of southern Europe, equatorial Africa and South America, 3 in the capillary passages of sea sand in the Channel, the Gulf of Thailand and off the coast of Peru, and one lives at a depth of 3521 liters in the Davis Strait. Such a scattered distribution of these primitive crustaceans, able to exist in such a variety of conditions, remains an unresolved mystery.

The practical importance of amphipods, as already mentioned, is very great and is determined by their use as food by many fish, including commercial ones. So, for example, in the Caspian Sea and the Sea of ​​Azov, they make up a significant part of the food of bream, sturgeon fry, in the Far East - many flounders, in the mouths of northern rivers - whitefish, omul, vendace, in fresh lakes - various whitefish, trout, etc. To improve the conditions for fattening valuable fish, amphipods were transported to many newly created reservoirs and lakes where they did not exist before.

Animal life: in 6 volumes. - M.: Enlightenment. Edited by professors N.A. Gladkov, A.V. Mikheev. 1970 .

amphipod
The most numerous are cladocerans, copepods, shells and heteropods.
crustaceans. All of them are active participants in biological processes,
occurring in the aquatic environment.
Feeding on a large number of dead remains of plants, animals, crustaceans
perform the function of biological water purification.
In turn, crustaceans serve as food for almost all fish.
Given the great natural and practical value of crustaceans, in recent years
about 40 of their species have been acclimatized, including amphipods, mysids, cumates, and decapods. Work in progress by artificial breeding as live food for
fish and waterfowl - daphnia, cyclops, brine shrimp, amphipods and others.
The most common and widely known to amateur anglers is
amphipod, or as they also call him, mormysh.
Amphipods live everywhere - in sea water, in fresh water, and in groundwater.
Some swim freely in the water column, while most are at the bottom.
The crustaceans burrow into the sand, make minks in the ground, build their own houses or
located in the vegetation.

Amphipods breed in large quantities, they not only purify water, but also
play a significant and even decisive role in the nutrition of almost all fish and
waterfowl.
Chemical analysis of these crustaceans shows that their body, depending on the species
contains up to 53 percent protein, 25 percent carbohydrates, 50 percent free
amino acids, up to 111 percent fat and other valuable substances.
Amphipods serve as a kind of indicators of water purity.
Where the water is dirty there are no crustaceans. They actively spread throughout the territory
reservoir, many physiologically important trace elements are iodine, zinc, cobalt, copper,
silicon, iron, strontium, lithium and others.
Amphipods feed the most diverse food: detritus, small living organisms, plants, organic remains.
They breed from spring to autumn.
They lay, depending on the type, size and age, from one, two to 150 eggs.
There are also crustaceans that lay much more eggs.

Amphipods live one or two years, although there are other data.
The sizes of adults of the most common amphipods in Russia reach:
males - from 12 to 15, females - from 8 to 10 mm.
The density of populations per square meter can vary from 8 to 12 specimens,
under ideal conditions, it can even reach two or three or more thousand.
Amphipods breed when they reach three months of age.
During her life, the female gives three generations of five to six litters, each generation
with a total potential production of approximately eight and a half thousand grams.

Amphipods are divided into many types, but, most importantly, they are all very useful.

Catch amphipods to use them as a hook attachment, you can
gauze or other small-meshed net, raking in coarse shell sand
near the shore, on which waves roll, as well as between stones overgrown
silky algae, and elsewhere.
You can also get crustaceans by lowering a bundle of straw to the bottom where they live,
potato tops or other succulent plants.
In winter, in a day, and in summer much faster, these bunches are densely populated with crustaceans,
which can be shaken onto the bedding.

The crustacean gammarus is well known to aquarists under the name amphipod and to anglers as mormysh. The distribution area and species diversity of the crustacean are huge - there are freshwater and marine ones, they live in all latitudes from the equator to polar waters, there are more than 4,500 varieties. As food for fish, the freshwater amphipod Gammarus pulex is mainly caught and harvested. This is a tiny crayfish, about 1 cm long, with a curved body clad in a segmented "armor". It lives in shallow water, burrowing into the sand, hiding in bunches of algae, under stones and driftwood. Gammarus feeds by filtering organic suspension and microscopic algae from the water.

The amphipod grows very quickly: in the warm season, molting occurs weekly, in the cold season - once every 2 weeks, but it also does not live long, about a year. Among the catch of crustaceans, tightly coupled couples often come across. This is a male, saddling a female, waiting for her next molt: only immediately after it does he have the opportunity to mate. The eggs develop on the abdomen of the female; after gestation, fully formed young are born, only tiny in size.

Gammarus is fed to aquarium fish fresh (but not live!), Frozen and dry. Anglers appreciate the mormysh as an excellent bait, and due to the rapid reproduction and growth, some types of amphipods are grown on an industrial scale for feeding fish in cages and preparing compound feed.


There are several ways to get amphipods:

• Collection. The simplest, but also unproductive way. In the warm season, we extract bunches of algae, stones and snags from under the water, quickly throw them ashore and collect the crustaceans by hand. With a good saturation of the pond with mormysh, even in such a laborious and primitive way, you can gain a decent amount in a short time;
• Trap. The method is very simple: hay or straw is collected in a bundle and placed under water (you need to place a load inside and tie a rope so that you can remove the trap from the water). After a few hours, you can remove the bunches from the water and simply shake out the crustacean that has huddled between the straws;
• trawling. A burlap cloth (necessarily natural, hemp or hemp) is tied to a long shaft and stretched along the bottom. Frightened crustaceans rush about in a panic, clinging to the burlap with their paws. The amphipods are assembled by hand;
• Net fishing. If there are thickets of filamentous vegetation at the bottom, then gammarus can be caught with a simple net made of a nylon stocking. We drive the net directly on the grass. A frightened crustacean tries to escape by swimming and settles on a stocking. But at the same time, a lot of “passing” prey comes across, so it is quite possible that the catch will have to be sorted.

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Amphipod can be kept alive for a long time. This requires soil and water from the reservoir where it was caught. You can keep crustaceans in a bucket, changing a third of the water daily (you can use settled tap water, the amphipod will withstand its gradual change). Forced aeration should be provided whenever possible: a large number of arthropods consume a lot of oxygen. Mormysh will live for several days on the bottom shelf of the refrigerator, wrapped in a damp cloth. It is only necessary to rinse the bundle with cool water every day.

Preparing a frozen gammarus is simple: in a plastic bag, the amphipod, previously well spilled with hot water (but not boiling water), is distributed in an even layer about a centimeter. Then it goes to the freezer for 2 weeks - this will ensure the death of pathogenic organisms that can provoke an epidemic in the aquarium. Frozen mormysh does not lose its nutritional value for about a year.

Mormysh can also be dried in the oven, but a more gentle and natural way is recommended: on gauze stretched over a wooden frame and suspended. This ensures uniform drying on all sides. The necessary conditions are the presence of a good draft and the absence of direct sunlight. It is necessary to distribute the amphipod in an even layer, "thick" in 1-2 crustaceans. Such a “snack” is stored for a long time, but after 3-4 months it begins to seriously lose nutritional value, so you should not store too much.

Breeding
Gammarus feels good in captivity and, in the presence of feeding, is quite capable of breeding. They are kept in small containers with Java moss and Riccia as food and shelter. Feed the crustacean with a small amount of vegetables or oatmeal scalded with boiling water. With a high density of mormysh, good aeration is required.

Gammarus feeding
You can feed fresh amphipods only if you are completely sure of its safe origin: bred in captivity or caught in a reservoir where there is guaranteed no fish. Before feeding, the crustacean is soaked for 10 minutes in hot water to soften the shell. Boiling water should not be poured - this will destroy most of the nutrients.
Frozen crustaceans are also poured with hot water for the same purpose.

Dry amphipods are fed to small fish and fry, after rubbing it in the fingers. This type of food should not be abused in any form: because of the strong chitinous shell, the amphipod is an excellent ballast food, that is, it cleanses the intestines. But for the same reason, its use more than 2 times a week is undesirable.

"Allergy" to the aquarium
For many people, crustaceans (crayfish, shrimp, crabs) are the strongest allergen. Bokoplav is no exception. There are frequent cases when parents, having acquired fish for a child, begin to notice manifestations of allergies in children and associate them with an aquarium, sinning on the characteristic smell emitted by an artificial reservoir. In fact, the cause is often a reaction to dust from crushed dried gammarus. Therefore, to solve the problem, it is worth giving up feeding pets with this crustacean without getting rid of the aquarium.

In different parts of our country they are called differently: "stonoga" in the Caspian Sea, "mormysh" - in the Urals and Western Siberia, "barmash" - in Baikal and Eastern Siberia. On Baikal there is an ice fishing for omul in winter - "barmashenie".

Amphipods from the surrounding lakes are brought alive in barrels to Baikal, holes are punched in the ice and crustaceans are thrown in handfuls, thus attracting the omul, which they catch by hooking with special hooks.

Where do amphipods live?

Often, semi-land marine amphipods lie on their side at the very edge of the water on the wet sand of the sea coast. Sometimes they form here a moving thick layer, individual crustaceans of which periodically jump out of the crowd. When a large animal or person approaches, the amphipods jump like fleas, pushing off the surface with their abdomen and jumping legs. During the day, sea fleas hide under rocks or algae, and at night they actively move along the beaches, looking for dead algae that they feed on. They breathe with gills and can only exist in a humid atmosphere. On the Commander Islands, sea fleas hibernate high above sea level, under a thick layer of snow.

Amphipod abilities

The ability of sea fleas to navigate by the sun is remarkable. Scientists have conducted such an interesting experiment. Amphipods were placed in the center of a large transparent vessel. The rest of the space of the vessel was divided into sectors by partitions. With the help of a compass, the exact position of each sector relative to the sea and the sun was determined. After a short time, all the crustaceans gathered in the sector facing the sea. It turned out that at every hour of the day the crustaceans move at a certain angle to the sun, and at night to the moon. In the dark, they are unable to navigate. At the same time, crustaceans living in different parts of the coast are adapted to orientation with respect to the sun at different angles, depending on the bend of the coast. Regular changes in the angle between the light source and the direction of movement of the animal during the day can be considered one of the best examples of the existence of the so-called "biological clock", i.e. natural daily changes in the characteristics of the organism.

Very interesting abilities were found in the deep-sea amphipod hyperiopsis. Its jaws, unlike the jaws of other amphipods, are sharply asymmetric: the left one is noticeably larger than the right one. The palp of the left jaw is swollen, its inner surface is equipped with blunt teeth, and the convex outer part is a resonator. The palp of the right jaw also has teeth, with which the crustacean can pass along the teeth of the left palp, producing chirring sounds. The ability of amphipods to make and perceive sounds helps them gather in flocks in conditions of absolute darkness of great ocean depths. In amphipods of another closely related species, males make chirring sounds to attract females.

Many amphipods willingly and quickly burrow into the ground. At the same time, they stick antennas into it and begin to rake it with their pectoral legs, discarding particles with their prehensile front legs. Sometimes it happens at great speed. The ability to burrow into the ground has made it easier for some species to spread from the seas up rivers, because once they burrow, the crustaceans can resist the flow of the river and not drift down. Thus, the amphipod populated the entire Volga up to its upper reaches, spreading from the Caspian Sea.

Most amphipods are omnivores, eating living and dead plants, rot, carcasses, and animal remains. They bite off pieces of food with their mandibles and grind them, and the jaws retain small particles, preventing them from falling into the water. Some species can obtain food by filtration. When the wave begins to move away from the shore, the crustaceans sit in the ground, sticking out the front end of the body from it, when the ground is exposed, they burrow into it entirely. All this happens with every wave.

The practical significance of amphipods is very great and is determined by their use as food by many fish, including commercial ones. In the Caspian and Azov Seas, they make up a significant proportion of the diet of breams, young sturgeons, in the Far East - many flounders, in the mouths of northern rivers - whitefish, omul, vendace, in fresh lakes - various whitefish, trout and other fish. To improve the fattening of fish, amphipods were specially brought into many newly created reservoirs.