Wedding

Aquatic animals of rivers. Coastal animal habitat. Why are frogs so wonderful?

Rivers, freshwater lakes, reservoirs, streams and swamps are inhabited by thousands of species of living organisms: from microscopic ciliates to giant fish and large freshwater birds.

Interestingly, of the total amount of water on the planet, fresh water makes up only 3%. Despite such an insignificant figure, the freshwater fauna is extremely diverse, and its most interesting representatives are worth getting to know better.

Freshwater fish

Of all fish known to science, about 41% of species live in fresh water. Among them are anadromous (anadromous) species that live in the seas, but breed exclusively in fresh water, for example, salmon and herring. Catadromous fish are another matter; on the contrary, they spawn in salty waters and then return to their native rivers. A striking example of this is the river eel - a ray-finned fish with a serpentine body.

And there are exclusively freshwater species, for which even a fraction of a percent of salt in the water becomes destructive, for example, the endemic fish of Lake Baikal - the Baikal omul and burbot - the only freshwater species of the order of cods. What other fish live in fresh water?

Pike

This is a predatory fish known to everyone, the heroine of fairy tales and legends. The spine of the famous Heilbronn pike is kept in the cathedral of the German city of Mannheim. They say that King Frederick II of Germany caught this pike in the fall of 1230, ringed it and released it. The fish was caught only in 1497, when it grew to 5.7 m!

Pike live in thickets of stagnant and low-flowing fresh water bodies of Eurasia and North America, and are occasionally found in desalinated areas of the seas.

photo of pike.

Som

Another large animal of freshwater bodies of water, which, however, can live in the salty waters of the Aral Sea. Modern catfish have become smaller, but in the old days fishermen caught specimens up to 3-5 m long and weighing up to 400 kg.

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In Rus', they didn’t like catfish, they were afraid of them, they called them “the devil’s horse,” they disdained meat and only made the filling for pies from their tails. And Muslims generally do not eat the meat of scaleless fish, including catfish.

See more photos and description: catfish photo.

Zander

A representative of the perch family, a typical predator with large fang-shaped teeth, an inhabitant of lake-river systems. The genus of pike perch includes 5 species, 4 of which are freshwater, and 1 is called sea pike perch.

Pike perch feed on bleak, sprat, minnows and various goby fish.

See more photos and description: photo of pike perch.

crucian carp

This is one of the most famous lake and pond fish of the carp family. The most common is golden crucian carp, but populations of silver crucian carp are sometimes formed only by females. In this case, they spawn with male carp, bream, tench or goldfish and again produce females.

Photo of crucian carp under water.

See more photos and description: photo of crucian carp.

Carp

A fairly large fish, over 1 m long and weighing about 20 kg, also known as common carp. Among carp there are both freshwater populations and semi-anadromous ones, which live in desalinated areas of the seas and spawn in rivers.

See more photos and description: photo of carp.

Beluga

This is the largest freshwater migratory fish: the weight of individual specimens reaches 500 kg! Beluga lives in the Black, Azov and Caspian seas, and spawns in rivers.

Beluga jumps out of the water.

Today this fish is on the verge of survival and its fishing is strictly regulated. Beluga lays black caviar, which is considered the most valuable of all sturgeons. In Russia, 1 kg of real beluga caviar costs about 400 thousand rubles, and abroad it is even more expensive.

See more photos and description: photo of beluga.

Golomyanka

An amazing fish with a transparent body, devoid of scales and a swim bladder, lives in the depths of Lake Baikal and is not found anywhere else. The golomyanka itself feeds on copepods, copepods, epishurs and amphipods, but it is readily eaten by all Baikal fish, for example, taimen, burbot and pike, as well as the Baikal seal. And the golomyanka does not spawn, but is a viviparous fish.

Squeaky killer whale

A very interesting fish of the catfish order, which, when pulled out of the water, begins to make creaking sounds. The fish's height does not exceed 35 cm, but it can stand up for itself, spreading very prickly spines in case of danger.

The creaking killer whale lives only in the fresh waters of China, Vietnam and Laos, as well as in Primorye, in Lake Khanka.

Crayfish, amphibians and reptiles of fresh water bodies

Some species of higher crayfish, snakes, lizards, turtles and frogs live in fresh water. For some, rivers, lakes and swamps are their home throughout their lives, others need water during the breeding season, others simply swim well and hide in the water from enemies.

Crayfish

Broad-toed and narrow-toed crayfish are common animals of freshwater bodies, living in clean, low-lying waters. In recent years, broad-clawed crayfish have begun to be replaced by an introduced species - the American signal crayfish, which is more resistant to the fungal disease - crayfish plague.

Already

The genus of snakes includes 4 species, among which the water snake is especially attached to water - an olive-colored snake with black spots, 1.3 to 1.5 m long. And the more common ordinary snake with characteristic “yellow ears” spends most of its life on land , although it swims beautifully and can do without air for up to 30 minutes.

See more photos and description: photo of a snake.

European marsh turtle

This reptile is widespread in fresh water bodies of Eurasia and northwestern Africa. Prefers slow-flowing rivers, canals, lakes, ponds and swamps, swims and dives well, and can go without oxygen for a long time.

The size of the European marsh turtle rarely exceeds 35 cm, it has a very long tail and a dark shell with small yellow markings.

Triton

The genus of newts includes 8 species, among which the most famous is the common newt. These amphibians spend a lot of time on land, but in early spring they go to fresh water bodies to breed, where the females attach one egg to the leaves of underwater vegetation.

In water, newts eat mayflies and bloodworms; on land, they hunt for earthworms, but they themselves often become prey for waterfowl.

Freshwater birds

Many waterfowl spend most of their lives in fresh water bodies, having all the necessary adaptations for this: membranes between the toes, dense plumage and a developed coccygeal gland, which secretes a fatty secretion to lubricate the feathers.

dabbling ducks

This is an extensive genus of Anseriformes birds, including more than 50 species. You are probably familiar with teal, mallard or tufted and gray duck, but many people have no idea about birds such as pintail, killer whale, shoveler or wigeon.

All these are river or noble ducks, who like to settle in the coastal zone of fresh water bodies and on muddy shallows.

Semi-footed goose

The only species of the genus and family of semi-footed geese with poorly developed swimming membranes. These are large geese up to 90 cm in size with contrasting black and white plumage and orange paws. These birds live in the floodplains and river valleys of Australia, Tasmania and New Guinea.

Royal heron

Another name for the bird is shoebill. This is the only species of the genus and family of shoebills that lives only in the swamps of East Africa. With their beak, which resembles a wooden shoe with a sharp hook, the birds deftly snatch their favorite food from the water - freshwater protoptera fish, which, by the way, are popular with the local population because of their very tasty meat.

Royal herons also eat frogs, small turtles, catfish and tilapia.

Canada goose

This is one of 8 species of black geese (geese), living in swamps, along the banks of rivers and reservoirs. The size of individuals in different parts of the range ranges from 55 to 110 cm. The head and neck of the birds are black with white spots on the cheeks and throat, the back is dark brown, and the belly is white.

The historical homeland of the Canada goose is North America, but these birds were introduced and successfully took root in Europe and New Zealand.

Toadstools

Today, the genus of grebes includes 8 species of birds that are very similar to loons. But unlike the latter, the paws of grebes are devoid of swimming membranes, but each finger is equipped with a leathery fold resembling a blade.

The best known is the great grebe or great grebe, which lives in lakes and ponds in Europe, Asia, the northern regions of Australia, New Zealand and Africa.

See more photos and descriptions: photo of the great grebe.

Among the animals of fresh water bodies, one cannot fail to mention the water shrew, a very rare species - the Chinese alligator from the Yangtze River, the otter, the beaver and, of course, the capybara - the largest modern rodent.

Ecology

Freshwater is a fragile but life-rich ecosystem. Compared to the amount of salt water on the planet, there is much less fresh water. Fresh water is vital for humans, so historically people tried to settle closer to lakes and rivers in order to freely use water. Not only fish live in fresh waters, but also a large number of mammals that breathe air, but cannot live without an aquatic environment. Learn about the largest and most interesting inhabitants of lakes and rivers from around the world.

These large mammals cool off by immersing their massive bodies in cool African ponds, rivers and lakes for long periods of time - up to 16 hours daily. Although they can hold their breath for half an hour if necessary, hippos usually stick their head out of the water. At night, hippos stop taking baths and go to browse the grass. If animals remain in the sun for a long time, they will quickly become dehydrated.

The hippopotamus, or hippopotamus as it is also called, has sharp fangs that can reach up to half a meter in length. They show their fangs to each other to determine which animal is dominant. Sometimes displaying powerful teeth is not enough, so animals get into bloody fights. Hippos are quite dangerous to humans.

Manatees live in shallow, warm river waters and can also live in salt water. These large mammals reach a weight of 600 kilograms. They are born underwater and never leave their home waters until death, but they are forced to swim to the surface of the water every few minutes to breathe air. Known as sea cows, manatees are herbivores that feed on a variety of marine plants, including algae and others. Several species of manatees live along the Atlantic coast of America, in western Africa and in the Amazon River.

The muskrat is a resident of wet areas, swamps and ponds, where it builds tunnels along the banks. The body length of this large rodent is about 30 centimeters, and its flat tail is twice as long as its body. Muskrats, or musk rats, are well adapted to life in water and begin to swim at the age of 10 days. They are well known for their communication abilities, able to exchange information with each other, and warn of approaching enemies with the help of a distinctive smell - musk.

There are many seals in the world, but only one species is truly freshwater - the Baikal seal. The animals live on Lake Baikal, Russia, the deepest lake in the world. Although new generations of Baikal seals are born every year on the shores of the lake, these animals are in serious danger of extinction. One of the reasons is illegal hunting, as well as environmental pollution from paper and pulp mills and other industrial facilities located around the lake.

The charismatic Amazon dolphin uses echolocation to track fish and crustaceans in the murky waters of the Amazon River. During the annual floods, dolphins swim in flooded forests, hunting for prey between the trees. Dolphins are fairly easy to spot due to their pink or very pale colors. The color of dolphins and their natural curiosity make them easy prey for hunters who illegally capture these animals. In recent years, the population has declined significantly. The indigenous people of the Amazon, the Bouto people, have long believed that animals have superpowers and can transform into humans.

The world's largest rodent, the capybara or capybara, can grow up to 130 centimeters in length and weigh about 66 kilograms. These water-loving mammals reach this weight by feeding on grass and aquatic plants.

Physically, capybaras are very well adapted to life in an aquatic environment. They have webs between their toes that help them swim well. Animals can dive and stay underwater for 5 minutes or more. Capybaras are found in Central and South America in lakes, rivers and humid areas from Panama to Brazil and northern Argentina.

The Conservation Committee works with partners to preserve the natural habitat for capybaras, including the wet grasslands of Llanos. The group is working with local landowners to establish private reserves in critical habitat as well as public protected areas in the province of Nasanare in northeastern Colombia.

Capybaras' eyes, ears and nostrils are located at the top of their heads, so they remain on the surface when the animals swim. These social mammals travel and live in groups where a large male dominates. Together they protect their territories where they live and feed. People hunt and farm capybaras for their meat and skins. Some Catholics in South America equate capybaras with fish, so they allow the meat of these animals to be eaten during Lent.

Beavers are excellent engineers, second only to humans in matters of restructuring the landscape in their favor. Using powerful jaws and teeth, they cut down trees to produce wood and mud dams that are 1 to 3 meters high and over 30 meters long. Beaver dams block the path of rivers and streams and prevent them from flooding fields and forests. As a result, lakes are formed, which can be quite large. On lakes, beavers build huts from branches and mud, which they enter through underwater tunnels. Huts are needed to hide from enemies and store food supplies.

Although beavers are quite clumsy on land, they are excellent swimmers thanks to their webbed feet and long, flat tail-rudder, which allows them to reach speeds underwater of up to 8 kilometers per hour. The animals boast their natural swimming suit made of oily, water-repellent fur.

Beavers feed on aquatic plants, roots, leaves, bark and branches. Beavers have teeth that grow throughout their lives, so when they chew wood, this prevents their teeth from growing too long and curved. One beaver is capable of felling hundreds of trees a year. In 15 minutes, a beaver can knock down a tree with a diameter of 15 centimeters.

These water-loving mammals find great pleasure in swimming and diving. With the help of webbed feet they can swim quickly. They have special nostrils and ears that close in water, as well as water-repellent fur. Young otters begin to swim as early as 2 months of age. River otters live in burrows along the banks of rivers and lakes, where they can hunt fish.

The platypus is an incredible mixture: it has a furry body like an otter, a beak like a duck, webbed feet and a flat tail like a beaver. Like all these animals, the platypus is a strong swimmer and spends most of its life in the water. Unlike otters and beavers, platypuses lay eggs—only a couple of mammals on the planet do so. Male platypuses have poisonous stings on their hind legs. The animals dig holes near the shore and feed on dug worms, mollusks and insects.

An animal that lives in water for a period of time or its entire life. Many insects, such as mosquitoes, mayflies, dragonflies and caddisflies, begin their life cycle as aquatic larvae before developing into winged adults. Aquatic animals can breathe air or obtain oxygen dissolved in water through specialized organs called gills or directly through the skin. Natural conditions and the animals that live in them can be divided into two main categories: aquatic or.

Groups of aquatic animals

Most people only think of fish when asked about aquatic animals. However, there are other groups of animals that live in water:

mammals, for example (whales), sirenians (dugongs, manatees) and pinnipeds (seals, eared seals and walruses). The concept of "aquatic mammal" also applies to animals with a semi-aquatic lifestyle, such as river otters or beavers;
shellfish (eg sea snails, oysters);
(for example, corals);
(eg crabs, shrimp).

The term "aquatic" can apply to animals that live in both fresh water (freshwater animals) and salt water (marine animals). However, the concept of marine organisms is most often used for animals that live in seawater, that is, in oceans and seas.

Aquatic fauna (especially freshwater animals) are often of particular concern to conservationists due to their fragility. They are exposed to overfishing, poaching, pollution, etc.

Frog tadpoles

Most are characterized by an aquatic larval stage, for example, tadpoles in frogs, but adults lead a terrestrial lifestyle near bodies of water. Some fish, for example, the arapaima and the walking catfish, also breathe air to survive in oxygen-poor water.

Do you know why the hero of the famous cartoon "SpongeBob SquarePants" (or "SpongeBob Square Pants") is depicted in the form of a sponge? Because there are aquatic animals called marine animals. However, sea sponges do not look like a square kitchen sponge like the cartoon character, but have a more rounded body shape.

Fish and Mammals

School of fish near a coral reef

Did you know that there are more species of fish than amphibians, birds, mammals and reptiles combined? Fish are aquatic animals because their entire lives are spent in water. Fish are cold-blooded and have gills that receive oxygen from the water to breathe. In addition, fish are vertebrates. Most fish species can live in either fresh or saltwater, but some fish, such as salmon, live in both environments.

Dugong is an aquatic mammal from the order of sirens.

While fish live only in water, mammals can be found on land and in water. All mammals are vertebrates; have lungs; They are warm-blooded and give birth to live young instead of laying eggs. However, aquatic mammals depend on water to survive. Some mammals, such as whales and dolphins, live only in water. Others, such as beavers, are semi-aquatic. Aquatic mammals have lungs but no gills and are unable to breathe underwater. They need to come to the surface at regular intervals to breathe air. If you've ever seen what a fountain of water looks like coming out of a whale's blowhole, it's an exhalation followed by an inhalation before the animal dives back underwater.

Molluscs, cnidarians, crustaceans

The giant tridacna is the largest representative of bivalve mollusks

Molluscs are invertebrate animals that have soft, muscular bodies without legs. For this reason, many shellfish have a hard shell to protect their vulnerable bodies from predators. Sea snails and oysters are examples of shellfish. Squids are also classified as mollusks, but they do not have shells.

Swarm of jellyfish

What do jellyfish, sea anemones and corals have in common? All of them belong to cnidarians - a group of aquatic animals that are invertebrates and have a special mouth and stinging cells. The stinging cells around the mouth are used to catch food. Jellyfish can move around to catch their prey, but sea anemones and corals are attached to rocks and wait for food to approach them.

Red crab

Crustaceans are aquatic invertebrate animals with a hard chitinous outer shell (exoskeleton). Some examples include crabs, lobsters, shrimp and crayfish. Crustaceans have two pairs of antennae that help them receive information about their environment. Most crustaceans feed on the floating remains of dead plants and animals.

Conclusion

Aquatic animals live in water and depend on it for survival. There are various groups of aquatic animals, including fish, mammals, molluscs, cnidarians and crustaceans. They live either in freshwater bodies (streams, rivers, lakes and ponds) or in salt water (seas, oceans, etc.), and can be either vertebrates or invertebrates.

Help. Name the plants and animals of the rivers and got the best answer

Answer from Alyonushka[guru]
Flora and fauna of the Iput River
The flora and fauna of the Iput River is rich and diverse.
Plants in a pond can be divided into three groups:

The fauna is an important part of the biosphere of our planet. Together with plants, animals play an exceptional role in the migration of chemical elements, which underlies the relationships existing in nature.

Answer from Maxim volentir[active]
the reeds are blooming and the ducks are in them, then think for yourself

Answer from Ilya Gerasimenko[master]
plants: orchid, datura herb, predictor sage. rivers: Amazon, Nile, Volga, Ob, Dnieper, Oka, animals: giraffe, hippopotamus, lion, tiger, dog, parrot)

Answer from Vanya Meleshchenko[newbie]
thank you, I needed this too!

Answer from Olga Reutova[newbie]
thank you I have an exam and I need this most of all

Answer from Shambhal[newbie]
beavers too.

Answer from Ivan Ivanov[newbie]
1. Amphibious plants growing close to the water along the low bank: sweet flag, three-leaved butterfly, amphibian buckwheat, slender sedge, angustifolia cattail, water chastuha.
2. The main strip of macrophytes, emergent or semi-submerged plants: white water lily, yellow water lily, floating manna, common reed, common arrowhead.
3. Plants immersed in water: floating pondweed, hornwort, duckweed, trilobed duckweed, telores, spicata, elodea, water plague.
Different types of plants are grouped together depending on the depth of the reservoir in a particular area.
Above-water and underwater vegetation serves as a habitat for numerous aquatic animals. Predatory dragonflies among insects perch on the reed stems, and dark gray caddis flies nest nearby. In the evening, swarms of twitching mosquitoes gather over the water; long, thin-legged water strider bugs and shiny spinning beetles glide along the surface tension film, quickly run and dive; and how pond snails glide across the glass of an aquarium. Here, in the thickets, the pupae of many insects turn into adult insects. The fauna on the underside of the leaves is very diverse: translucent hydras, bryozoans, pitcher moths, rainbow beetles, and beauty dragonflies settle here, and caddisflies lay their eggs here. Mollusks crawl slowly along the underside of the leaves: pond snails, calyx worms, small ciliated worms.
Various animals live in reservoirs - representatives of the class of mammals or animals, which belong to various orders and families. Here are some of them: the rodent order, the beaver family, the river beaver. Lives mainly along the banks of slow-flowing forest rivers, oxbow lakes and lakes; It is important for him to have floodplain herbaceous and tree-shrub vegetation near reservoirs - willow, poplar, and aspen.
Order Carnivores, mustelidae family, European mink and river otter. Several decades ago, on the territory of the Novozybkovsky region in the Iput River basin, there was an acclimatized species - the American mink, which has now been replaced by the European mink, destroying it. This valuable fur-bearing animal must be protected. The fur of the otter, which leads an aquatic lifestyle, is also highly valued.
Representatives of bony fishes are numerous. Among them are: common roach, ide, rudd, tench, gudgeon, bleak, bream, common loach, river burbot, silver carp and others.

On a fine, sunny day, the pond appears lifeless from a distance. Its surface is calm, there are no waves or the slightest movement. But take a closer look - this quiet pond is full of life. And if you fish among the plant thickets with a net, you can fill the aquarium of the school living corner with dozens of living creatures. By observing freshwater animals in an aquarium, you learn a lot about their life in nature.

Freshwater hydra is not difficult to find among underwater thickets in ponds, river backwaters, and small lakes. Hydra belongs to the lower multicellular coelenterate animals. In the seas and oceans it has many relatives - jellyfish, corals, sea anemones. In fresh waters, hydra is the only representative of coelenterates. To get a better look at the hydra, you need to arm yourself with a magnifying glass. Its pinkish or brown thin body in the form of an oblong sac, only 20-30 mm to 1 cm long, is attached to the plant by its lower end - the sole. At the other end of the hydra's body is a corolla of 6-8 tentacles that surround the mouth of this animal. If the hydra is hungry, its body extends to its full length and the tentacles hang down. And on the tentacles there are special nettle (stinging) cells. When irritated, thin stinging threads containing a caustic substance are released from these cells and pierce the body of the victim. If a crustacean (cyclops or daphnia) or other small animal accidentally touches a tentacle, it will receive a blow from the stinging threads and will be paralyzed by the poisonous liquid contained in them. When swallowing prey, the hydra's body shortens.

Hydra easily restores lost body parts. Even severely wounded and reduced to rags, she survives. If even a piece of the body survives, the hydra will be restored. Hydra reproduces sexually and by budding. It usually buds in the summer. The grown bud, which has not yet separated from the mother’s body, has already formed a mouth and tentacles, and it itself catches prey. By autumn, male and female reproductive cells are formed in the hydra and fertilization occurs. During the winter, all hydras in the reservoir die, and their new generation no longer develops from buds, but from overwintered fertilized eggs.

Under favorable conditions, hydras cover all underwater objects like pink velvet! Such mass reproduction of hydras in fishing ponds is harmful: hydras eat fish food and can capture with their tentacles not only crustaceans, but also tiny fry that have barely left the eggs.

In fresh water bodies on the muddy bottom and among underwater vegetation there are many different worms. Most of them are very small animals, only some of them exceed 20 cm in length. The most noticeable among aquatic worms are leeches. Leeches are classified as ringed worms.

Many people are afraid that a leech might become attached to them while swimming. But this fear is unfounded. In the waters of the central zone of the USSR, almost all leeches are harmless to humans. Their weak jaws are not able to bite through our skin. Only the medicinal leech, found in the south of the European part of the USSR, can suck human blood. It is easily distinguished by its greenish back with red specks. The length of such a leech is about 12 cm.

In ponds and lakes in the middle zone there are small brownish leeches, no more than 6 cm long, and almost black large ones, up to 12 cm long. False Kon leeches are a living barometer. By placing them in a glass jar with water, you can observe how the behavior of leeches changes depending on the weather. Before good weather, they lie calmly on the bottom or swim leisurely. In the face of a strong wind, leeches scurry restlessly back and forth. If it rains in the next 24 hours, they either lie motionless in the water, or, half sticking out of the water, hang vertically one next to the other. Before a thunderstorm, leeches begin to wriggle convulsively and stick to the glass above the water or even to the glass lid of a jar.

The method of movement of leeches is interesting. There are suction cups on both ends of the worm, with which it firmly attaches itself to underwater objects. The front suction cup holds the mouth. The leech moves like this: it sticks to something with its front end, bends into an arc, brings the back end of the body closer to the front, sticks with its back end and begins to look for a new support point with its front end. But the leech swims well, bending its flat, ribbon-like body in waves.

False horse leeches most often feed on snails and worms, which they suck out or swallow whole. Most leeches do not protect their eggs. Thus, the large false-cone leech lays cocoons with eggs in damp soil at the very edge of the tree, and the small one glues them to the underside of floating leaves. The walls of the cocoons of the lesser false-cone leech are so thin that the development of unhatched tiny leeches can be seen through them.

The medical leech is so named because it has long been used by doctors when it is necessary to remove a certain amount of blood from a patient’s body. The medicinal leech has three sharp jaw plates in its mouth. When a leech attaches itself, these plates cut thin wounds in the skin. The leech's intestines have large, pouch-like projections that swell greatly when the leech sucks blood. In an hour, the leech sucks up to 50 g of blood. Her saliva contains substances that prevent the blood being sucked from clotting. In the intestines of a leech, blood is digested gradually, and therefore, having pumped, the leech can remain without food for a long time. In pharmacies, medicinal leeches are kept in clean water and not fed at all.

The shell of a snail, or, as it is scientifically called, a gastropod, is solid, with one hole at the bottom. Usually it is twisted 5-7 turns in a spiral, expanding downward. Inside the shell is the soft, slimy body of the mollusk. Most of it can protrude outward - this is the head and a wide, flat bottom “leg”, with the help of which the snail glides like on a ski. If the snail is crawling calmly, a pair of tentacles and tiny dark eyes are visible on its head.

Most freshwater snails breathe atmospheric air. These include pond snails with a shell as tall as a tower, delicate physes, which are often kept in aquariums, and reels with a shell wrapped like a wind pipe in one plane.

Having secured itself on the underside of the surface water film with the help of a “leg,” the snail opens its breathing hole and takes in air. Under its skin there is a so-called pulmonary cavity, where the air collected by the cochlea for breathing is stored and consumed. There are snails in our reservoirs that breathe not atmospheric oxygen, but oxygen dissolved in water. The lawnfish has a delicate feathery gill inside its shell. The little shutter has a gill that sticks out like a tiny feather when it crawls.

Most snails lay eggs encased in a clear, gelatinous mass. The pond snail and the physa have a long, sausage-like clutch, while the reel has a flat cake-shaped clutch. In the meadow, the development of the young occurs inside the body of an adult snail and tiny snails are born. Aquatic snails feed mainly on algae, scraping them off rocks and plant stems with their small horny tongue. Therefore, snails are even specially placed in aquariums so that they clean the glass walls of algae.

In addition to gastropods - snails - in fresh water bodies there are bivalve mollusks called shells. Some of them are very small. Yellowish globules no more than 8 mm in diameter; white peas similar to grains of chalk - 2-3 mm. The largest shells in our rivers and lakes are toothless and pearl barnacles. In sandy shallow waters, pearl barley is sometimes found in large numbers. Usually the pearl barley is almost entirely immersed in sand, and only the rear end of its shell is visible from it. The mollusk is motionless, only the slight movement of water from the slightly open shell flaps shows that it is a living creature. If you touch the sink, the valves will close and the water flow will stop. While the pearl barley is alive, it is impossible to open its shell: two strong muscles keep the valves closed. But in a dead mollusk the valves move apart easily.

Inhabitants of fresh water in the middle zone: 1 - mosquito; 2 - kingfisher; 3 - water strider; 4 - mayfly; 5 - dragonfly; 6 - skin of a larva, dragonfly; 7 - lion fly; 8 - already ordinary; 9-water scorpio; 10 - pond frog; 11 - false horse leech; 12-mosquito larva; 13 - crested newt; 14 - rowing boat; 15 - tadpole; 16 - swimmer; 17 - swimming beetle larva; 18 - Cyclops; 19 - crucian carp; 20 - supreme; 21 - rod-shaped ranatra; 22 - daphnia; 23-swamp turtle; 24 - pearl barley; 25 - dragonfly larva; 26 - dwarf catfish; 27 - amphipod; 28 - barley leaf; 29 - pond snail; 30 - water lover larva; 31 - coil; 32 - cancer.

The shell of the pearl barley is brown and inconspicuous on the outside. Often it is covered with a growth of algae, sometimes small sponges settle on it, but inside the shell, cleared of meat, shimmers with the rainbow play of mother-of-pearl and is very beautiful. The body of the pearl barley is enclosed between the shell valves in a spacious cavity. On both sides of it, tightly adjacent to the shell, lie two folds of skin. This is the so-called mantle. The mantle and delicate gills, hanging on the sides between it and the body, like lace curtains, are covered with microscopic cilia. The movement of the cilia creates a flow of water in the cavity limited by the mantle. It enters this cavity, washes the body of the pearl barley and its gills and comes out again. A continuous flow of water brings the mollusk oxygen and food dissolved in it. Pearl barley feeds on the smallest particles of dead plants, microscopic algae and ciliates.

The pearl barley moves little, often at night, and very slowly, at a speed of no more than 20-30 cm per hour. Like all mollusks, it moves with the help of a muscular “leg” shaped like a plow. That’s why pearl barley leaves a mark on the sand in the form of a deep wavy groove.

Dragonfly transformations. The larva emerges from the water (1); the skin on its back bursts, and the chest and head of the future dragonfly rise from the crevice like a mound (2); then the dragonfly extends its legs (3) from the skin to its abdomen (4). Having freed them, it hangs upside down for some time. Having rested and strengthened, the dragonfly crawls out of the skin entirely. Before the observer's eyes, the dragonfly's wings increase, reaching normal sizes (5), and it flies away.

Our river shells live for a long time - up to 10-15 years. During this time, the shell of the mollusk grows both along the edge and in thickness. On the outside of the shell you can distinguish growth rings, and with some skill you can even determine the approximate age of the mollusk.

Of the crustacean animals that live in our fresh waters, the largest is the common crayfish. Its length reaches 20 cm. The body of the crayfish is clearly divided into the front part - a fused cephalothorax, covered with a brown-green durable shell, and a segmented abdomen with a wide fin at the end. There are two pairs of whiskers on the cancer's head. The first pair are short double antennae. These are the organs of smell and touch. The second pair of mustaches is more noticeable. They are longer than the first ones. Cancer uses them only for touch. Near the mouth, the crayfish has several pairs of complex jaw appendages, with which it finely grinds pieces of food so that it passes through its small mouth.

A pair of claws is attached to the crayfish's chest. The muscles of the claws are very strong, and it is not easy to unclench them if the cancer clings to the finger. The claws serve the crayfish both to protect itself from enemies and to hold food in front of its mouth. Claws are special legs adapted for grasping; Cancer does not use them when walking. Behind the claws on the cephalothorax of the crayfish there are 4 pairs of walking legs. There are small tweezers at the ends of the first and second pair. Small abdominal legs can be seen on the abdomen of the crayfish. The cancer constantly moves them, driving water to the gills lying under the chest shell. Cancer is very sensitive to the purity of water and the amount of oxygen dissolved in it. In an aquarium, if the water is not changed often enough, the crayfish will die quickly.

Cancer makes a hole for itself at the bottom under a stone or a piece of driftwood and spends the whole day in it, with only its long whiskers exposed. In the evening he crawls out of his shelter in search of food. Crayfish feeds on small sedentary animals, algae, and often eats the corpses of fish, snails and worms.

Frog development. Tadpoles that have just hatched from eggs (1) hang in groups on aquatic plants (2), each has a sucker and external gills; gradually the external gills disappear (3, 4); then the legs appear - first the hind ones (5), then the front ones (6); gill respiration is replaced by pulmonary respiration, the tadpole comes to land, its tail gradually decreases (7), and the tadpole turns into a frog.

A durable shell protects the crayfish from enemies, but prevents it from developing - it restrains its growth. This is why, from time to time, the crayfish molts - it completely sheds the cover that has become tight. With great difficulty, he pulls out his claws and each of his many legs from his shell. It happens that they break off. Having shed its shell, the crayfish is very helpless for some time and can easily become prey for perch or pike. But soon the surface tissues of the cancer become saturated with lime, and a new shell appears on it.

The female crayfish carries eggs on her abdominal legs all winter, from December to May. Small crustaceans, having emerged from the eggs, remain under the mother’s abdomen for another 10-12 days and only after that begin to lead an independent life. In addition to the common crayfish, many crustacean animals live in our fresh waters: various amphipods, water lice, cladocerans such as daphnia, and copepods such as Cyclops. These small crustaceans are the best food for fish.

Fresh waters are home to many different insects - various beetles and bugs, and even more larvae of the same insects that live in the air as adults: dragonflies, caddis flies, mayflies, mosquitoes. Even the caterpillars of some butterflies live in water and feed on aquatic plants. Thus, some insects spend their entire lives, in all stages, in water, others live in the air, but lay eggs in water and their larvae develop in water.

The life of dragonflies is associated with the reservoir. One of the largest dragonflies in our country is the large rocker. She has a blue abdomen with brown spots and large transparent wings. On the sides of her head are large bulging eyes, each of which consists of several thousand individual ocelli. This allows the dragonfly, like many other insects, such as flies, to simultaneously see in different directions, notice prey, and navigate well during fast flight. The dragonfly grabs and devours its prey - small insects, including mosquitoes - in flight, gnawing them with its strong jaws.

To lay eggs, the female rocker dragonfly descends along the plant stem all the way to the water and sticks each egg separately into the underwater part of the stem. The larva emerges from the egg into the water. It looks so little like an adult dragonfly that only by seeing its life and transformation in an aquarium, one can be convinced that the larva and dragonfly are different stages of development of the same insect. Usually the larva sits motionless, clinging to some stem, or slowly moves along the bottom on long and thin legs. Its brown color makes it invisible among aquatic vegetation. But, having seen the prey, the larva throws out a stream of water from the intestine, quickly, like a rocket, swims forward and grabs the prey with its organ - the mask. The mask is a highly developed and mobile lower jaw. When the larva is at rest, the mask is pressed to the head and covers its lower part, like a real mask. An adult dragonfly does not have a mask. The rocker dragonfly larva lives in water for up to three years. During this time, she molts several times and becomes larger with each molt. Before the last molt, its length reaches 6 cm. Usually in June, for the first time in its life, the larva crawls out of the water and turns into a dragonfly. For two to three months, the dragonfly will fly quickly over the water, catch prey, lay eggs in the stem of an aquatic plant, and die in the fall.

Dragonflies and their larvae are beneficial: they destroy aquatic insects - mosquito larvae and larvae of predatory swimming beetles. Adult dragonflies destroy flies and mosquitoes. True, in fishery reservoirs, dragonfly larvae can cause some harm, as they also eat fish fry.

Larvae and pupae of mosquitoes also live in fresh waters - the common mosquito, the malaria mosquito, etc. The testicles of the common mosquito can easily be found in a ditch, in a pit with water, and even just in a barrel where water is stored for watering the garden. The testicles are so small that they would not be noticeable separately. The female mosquito glues several dozen testicles together, and they float in a tiny gray raft on the surface of the water. The larvae immediately find themselves in the water. These are tiny, 2 mm long, worm-like creatures. They, like the larvae of all dipterous insects, have no legs. They swim, convulsively bending their abdomen. The mosquito larva feeds on tiny algae, ciliates and bacteria, which it pushes towards its mouth with the bristles of its oral appendages. The larva grows quickly. In 5-6 days, it sheds its skin three times and its length reaches 8 mm. After the fourth molt, the larva becomes a pupa. Unlike the motionless pupae of butterflies and beetles, the mosquito pupa swims just as quickly as the larva. There is a fin on its short abdomen, and with each blow the pupa moves, tumbling in the water. The mosquito pupa does not feed; it lives on the reserves accumulated by the larva. But the pupa, like the larva, breathes atmospheric air and therefore must float to the surface of the water from time to time. After 3-4 days, the pupa floats to the surface for the last time, and a winged mosquito emerges from it. He is in a hurry to fly away from the water: the slightest breath of wind can throw him into the water, but the mosquito does not know how to swim.

The common mosquito is a blood-sucking mosquito. Female mosquitoes suck the blood of animals and humans. Males feed on flower nectar. Among the blood-sucking mosquitoes there is also the malaria mosquito - Anopheles. It is much more difficult to exterminate all adult mosquitoes than to destroy their larvae and pupae before they leave the reservoir. Oil is sprayed onto ponds, swamps and ditches containing water where mosquito larvae are found. Its greasy film floats on the surface of the water, clogs the respiratory tubes of larvae and pupae, and they quickly die.

But there are also types of mosquitoes that do not suck blood and are completely harmless. Fishermen and aquarium enthusiasts know, for example, the large red larvae of the mosquito - the so-called bloodworms. These larvae live by burrowing in the muddy bottom of a pond. There are many different beetles in our fresh waters. The largest of them is the swimming beetle. This is the most dangerous enemy of fish fry. The length of its body is more than 3 cm. The swimmer is a predator. It attacks every living creature, even quite large fish. Its main prey are tadpoles, insect larvae and snails. Even when well-fed, he continues to hunt: he will grab his prey, tear it apart with his jaws and throw it away. The diving beetle causes great devastation in ponds. A swimmer can stay under water for a very long time: it breathes from reserves of air drawn into the cavity under the elytra. The activity of the swimmer does not stop in winter. Under the ice, it continues to swim and feed. But swimmers breed only in summer. The female lays eggs underwater in plant tissue, inserting each egg diagonally into the stem. The yellowish larva of the diving beetle resembles an adult insect even less than the larva of a dragonfly. It has an elongated, worm-like, jointed body and a small head.

Due to its uncontrollable predation, the larva resembles an adult beetle. No wonder it is called the water tiger. It rushes at every living creature and plunges its long sickle-shaped jaws into it. The prey - a tadpole, a fish fry or the larva of another insect - soon freezes, and the diving beetle larva hangs on its victim and sucks it out. The thin jaws of the larvae are not able to chew prey, as the strong serrated mandibles of an adult beetle do. The larva releases caustic saliva into the body of its victim, which dissolves the muscles and other organs of the captured animal, and absorbs the liquefied food. An adult larva eats up to fifty tadpoles per day.

The larva must be handled carefully. If you remove it from the net with your fingers, it digs into the skin with its needle-sharp jaws. In order to develop into a beetle, the larva must go through the pupal stage. Before pupation, the larva restlessly crawls along the bottom of the reservoir near the shore, then crawls out onto the wet ground and climbs into some hole. There she sheds her skin and turns into a pupa. By the end of summer, the development of the beetle ends and it leaves the pupa shell. At first, the young beetle is completely light-colored and its covers are soft. Only after a week, when they harden, the beetle emerges from its underground cradle and descends into the water.

It's not just invertebrate animals that live in our fresh waters. In ponds, lakes and rivers you can see various frogs and toads. Their tadpoles are found in fresh water bodies almost all summer. In the spring, frogs and toads hold “concerts” near the water and lay eggs in the water. The warmer it is, the more vocal they are. Frog tadpoles complete their development in water within a few weeks. But only the toaded firebird, pond frog and lake frog live permanently near water bodies. An ordinary grass frog, having laid its eggs in the water, moves away from the reservoir. Also, only until the beginning of summer can you find newts in the pond in their bright spring plumage. And then, until autumn, only newt larvae live in the water. They are easily distinguished by the branched gills on the sides of their heads.

Of the reptiles, it is associated with water; he hunts frogs here. The marsh turtle is found in the rivers and lakes of the southern regions of our country. In nature, she is not nearly as clumsy as in captivity. In the water, the turtle moves with amazing speed. There are many types of fish in fresh waters. Some of them live and develop in the seas and oceans, and enter rivers only to lay eggs. But most freshwater fish spend their entire lives in rivers, lakes and ponds.