Who eats a pond snail in a pond. Big pond. Reproduction and development

The family of pond snails includes well-known and widely distributed throughout the world freshwater lung molluscs.

Of the large number of species belonging to this family, the common pond snail is best known for its large size, the largest specimens of which reach 7 centimeters. From early spring to late autumn, these snails can be observed in ponds, in river backwaters, and small lakes. It is interesting to watch how these bulky snails crawl on aquatic plants or along the bottom of a reservoir. There are especially many of them in the middle of summer among the floating leaves of egg capsules or water lilies.

Pond snails are omnivorous, therefore, crawling along the leaves and stems of aquatic plants, they scrape off radula algae from them, and at the same time they absorb small animals that they come across on their way. Prudovik is one of the most voracious inhabitants of fresh waters. It eats not only plants and animals, but also corpses.

You can often see how a pond snail, having risen to the surface of the water and hung to it from below with a wide sole of the foot, due to the surface tension of the water film, slowly and smoothly slides in this position. It is not in vain that pond snails rise to the surface of the water. Although they are aquatic organisms, but, like all pulmonary mollusks, they breathe with the help of a lung and are forced to rise to the surface in order to “sip” air. The respiratory opening of the pond snail, leading to the lung cavity, is wide open. The presence of lungs in pond snails indicates that these animals originated from land mollusks and have already returned to living in water for the second time.

Reproduction of pond snails

When mating, pond snails mutually fertilize each other, since, like all lung mollusks, they are bisexual creatures. Snail eggs are laid in the form of long, gelatinous, transparent cords, which are glued to various underwater objects. Sometimes eggs stick even to the shell of another individual of the same species. Pond eggs are a complex formation, since the egg cell is immersed in a mass of protein, and is covered with a double membrane on top. The eggs, in turn, are immersed in a slimy mass, which is dressed in a special capsule, or cocoon. A strand departs from the inner wall of the cocoon, attached at the other end to the outer shell of the egg, as a result of which it appears as if suspended from the wall of the cocoon. The complex structure of the egg clutch is also characteristic of other freshwater lung molluscs. Thanks to these devices, the egg is provided with nutritious material and protected by powerful shells. Inside these shells, the development of pond snails takes place without the stage of a free-swimming larva. It is likely that such protective adaptations of the eggs of pond snails were inherited from their land ancestors, where these adaptations were more important than when living in water.

The number of eggs in a clutch varies quite widely, as does the size of the entire clutch - the slimy cord. Sometimes you can count up to 270 eggs in one cocoon.

The pond snails are extremely variable, and the size of the mollusks, the shape of the shell and its thickness, and the color of the legs and body vary greatly. Along with large representatives, almost dwarf forms are known, undergrown due to unfavorable conditions and malnutrition. In some pond snails, the shell has thick, hard walls; there are also forms with an extremely thin and fragile shell that breaks at the slightest pressure. The shape of the mouth and whorl is highly variable. The color of the legs and body of the mollusc varies from blue-black to sandy-yellow.

This "tendency" to variability played a big role in the evolution of pond snails. Within the species, a large number of local varieties have arisen that differ in these characteristics, and it is often very difficult to determine whether this is a geographical subspecies or a variation due to specific habitat conditions in a given reservoir.

Types of pond snails

Along with the common pond snail, a permanent inhabitant of our inland waters, there is another, also extremely variable species - the eared pond snail. In addition, ovoid pond snail, marsh pond snail and some others live in stagnant reservoirs.

Interestingly, pond snails living at considerable depths have been found in the deep lakes of Switzerland. At the same time, they are already deprived of the opportunity to rise to the surface to breathe air and have developed another adaptation. The lung cavity of these snails is filled with water, and they breathe oxygen dissolved in water. The absence of gills in pond snails, unlike primarily aquatic mollusks, again proves their origin from land snails.

Close to pond snails is the only representative of our fauna from the genus mixas, which differs from them in a very thin and fragile shell, almost completely covered with a mantle. Thus, the shell of this mollusk turned from the outer into the inner. These snails live mainly in floodplain ponds and lakes, where they sometimes breed in large numbers. However, in the middle of summer, snails disappear, as their life cycle ends in one season.

After starting a new aquarium, novice aquarists often face the problem of pollution, the appearance of unwanted algae. There are many ways to clean the aquarium tank, the best of which, perhaps, is biological, that is, adding natural cleaners to fish. Often, fish owners resort to the help of pond snails. They not only help fight pollution, but are also interesting in terms of observing their behavior.

Description, types

The pond snail (lat. Lymnaeidae) is a snail belonging to the genus of pulmonary molluscs. As the name implies, it lives in fresh water bodies with stagnant water or water with a very slow current.

Did you know? Snails are among the most ancient animals on Earth. According to scientists, they appeared over 500 million years ago..

The body of the mollusk is divided into three parts: head, body and leg. The pond snail has a fine-spiral shell, on which there are five or six whorls, mostly twisted to the right. Left-handed are found in the inhabitants of New Zealand and the Sandwich Islands. The shell opening is large, rounded in front. The shape of the shell depends on what current is characteristic of the reservoir where the snail lives. Its dimensions range from 1 to 6 cm in height and from 0.3 to 3.5 cm in width. The body is tightly attached to the shell. The head of this mollusk is large. It has flat triangular tentacles with eyes on their inner edge. The hole through which the pond snail breathes is protected in the form of an outstanding blade. The color of the snail depends on the living conditions. The shell is usually brown. The head and body can be colored from black with a blue tint to yellow with a brownish tint.
In nature, the pond snail is represented by many species that live in the Northern Hemisphere, in Eurasia, North Africa, and North America. Some of its representatives can be found in geysers, sulphurous, slightly saline and salty waters. You can find them even at an altitude of 5.5 thousand meters in Tibet and at a depth of 250 m.

Did you know?The tiny snail brain is divided into four sections and is quite efficient. Scientists claim that these mollusks have the ability to make independent decisions. After conducting more detailed studies of two neurons that are responsible for the feeling of hunger and the decision to go for food, they decided to use this data to work with the simplest algorithms in robotics.

Each species is distinguished by the characteristic coloration of the shell, body, legs, as well as the shape and thickness of the shell walls, the shape of the whorl and mouth.

Let's take a closer look at the most famous species:

1. Prudovik ordinary, he is big. The largest in our area and the most famous representative of the family. The shell is elongated, conical, 4.5-6 cm long and 2-3.5 cm wide. It is twisted in a spiral with 4-5 turns, which quickly expand, forming a large hole. Its color is brown, the walls are thin and translucent; the body of the mollusk is greenish-gray. The species is widespread, found throughout the Northern Hemisphere in various freshwater reservoirs.
   
2. This species has an elongated, pointed to the top and strong shell. Curls twist to the right, have six to seven turns. The shell is thin, almost transparent, pale yellow. Its dimensions are small: length - 1-1.2 cm, width - 0.3-0.5 cm. The body and mantle of this pond snail are of light gray shades. There are dark spots on the mantle. The species is distributed on the territory of Russia, lives in ponds, swamps, puddles. It can live along the banks of drying water bodies.
   
3. Ear. So named because the mouth of the shell in appearance is very similar to the human ear. Its shell is small - 2.5-3.5 cm in height and 2.5 cm in width. Has thin walls. Painted in greyish yellow. Has up to four turns. The last turn is very large. The body is colored green-gray or yellow-green with numerous inclusions. The mantle can be monophonic - light gray, or spotted. The ear pond snail lives in various reservoirs, lives on plants, snags, stones.
   
4. ovoid or oval. Like the auricular pond snail, the ovoid shell curl makes up a third of the mouth. The shell has thin walls, so it is very fragile. In an adult, it is 2-2.7 cm in height and 1.4-1.5 cm in width. The shape of the mouth is ovoid. The shell is painted light pink, shiny and almost transparent. The body color is light gray or light olive. The mantle is also light grey. The natural habitat of the egg-shaped pond snail is lakes, quiet rivers. It can live both in the coastal zone and at depth.
5. In the swamp pond snail, the height of the shell reaches 3.2 cm, the width is 1 cm. In appearance, this species is similar to the common pond snail, but differs from it in that its shell has the shape of a sharp cone with a small hole. It is dark brown in color. In addition, the marsh one is smaller than the ordinary one: the height of the shell is 2-3 cm, the width is 1 cm. There are six to seven whorls on the shell. Her walls are thick. The body is greenish gray in color. The mantle is light. It lives in shallow water bodies - swamps, puddles, streams, ponds.
   
6. Frilled or frilled. It got its name due to the fact that its shell is completely or partially covered by a mantle. The shell of the raincoat is shiny, smooth. May be colorless, yellowish or yellow-horny. It is small in size, its height is 1.9 cm, width is 1.2 cm. It has 2.5-4.5 curls. The last one is very big. The shell is shaped like a ball. Mouth - oval, large. The body is painted olive with gray color with numerous inclusions. The mantle is yellow-brown or yellow-green with large light spots. Lives in lakes, quiet rivers, in shallow water.

Habitat in nature

In nature, common pond snails eat mainly plants. However, their diet can also include animal food (flies, fish eggs, etc.) and bacteria. They breathe, crawling out of the water to the surface. On the day they need to carry out from six to nine such lifts. Those snails that live at great depths are able to exist due to the air dissolved in water. They draw water into the lung cavity. Pond snails can swim - they turn the sole upside down and give it a slightly concave shape.

Did you know? Snails have no hearing and voice, very poor eyesight, but their sense of smell is well developed - they are able to smell food at a distance of about two meters from themselves. The receptors are located on their horns.

Under natural conditions, these snails can rarely be found idle, usually they are “in a hurry” somewhere, busy with something - for example, scraping algae from stones. The maximum speed they can develop is 20 cm per minute.
It is interesting that these mollusks are able to survive when the reservoir dries up, sealing the shell with a dense film, as well as when the pond is covered with ice - after thawing it, they come to life and continue their vital activity. The average life expectancy of an aquarium pond snail is two years, in the wild it is nine months.

Prudovik is an unpretentious aquarium inhabitant. The main conditions for its maintenance are water temperature not lower than 22 ° C, its moderate hardness and weak light - preferably fluorescent with a minimum power.
With warmer water, snails will breed more often and actively, and this is not desirable for home aquariums. The size of the aquarium is not critical. The soil is rocky. It can be pebbles or coarse sand.

Special cleaning for shellfish is not required. All you need is the standard procedures that every aquarist must follow:

• weekly water change by 30%;
• aeration;
• filtration.

Nutrition, mineral supplements

Every aquarium owner who is going to place a pond snail in it will be interested in the question of what he eats and where to get food for him. There will be no problems with this, since he can eat both what the fish did not eat, and their excrement, rotten plants. A person can prepare for him a salad of finely chopped greens, cabbage, zucchini, pumpkin, tomatoes, and other vegetables and fruits.
With the addition of pond snails to the aquarium, you should be careful, because when they reach adulthood, they can be very voracious and eat most of the underwater vegetation. Occasionally, snails will need to be fed with mineral supplements. The main thing for them is calcium, so you can sprinkle them with crushed eggshells, chalk, sepia.

Important! Do not plant pond snails in a tank where soft and succulent underwater plants grow. It threatens the death of the latter. These snails are too tough for only algae with hard, dense sheets.

Compatibility with other inhabitants of the aquarium

Diseases

Snails rarely get sick. But they themselves serve as a source of infectious ailments for other aquarium inhabitants. Moreover, the danger lies in the fact that usually the presence of an infection in the body of a mollusk does not affect its appearance in any way, therefore it is not always possible to immediately determine whether it is dangerous for fish or not. In a small pond snail, the most common disease is fungal infection - its shell is covered with a white coating.
Treatment will consist in baths with the addition of salt solutions or potassium permanganate. Also, if the mollusk does not consume the necessary amount of vitamins and minerals, the walls of its shell can become thin and get damaged. When observing this problem, it is worth feeding the snail with substances containing calcium. Small cracks will disappear on their own some time after the start of treatment. But the deep ones will need to be “glued” with a special preparation sold in zoological stores.

Breeding

Pond snails reach sexual maturity at six to eight months. Since they have no sexual differences, representatives of the pond family reproduce by laying eggs, usually from 20 to 130 per clutch. This process can occur in them several times a year, and in a lifetime one individual is capable of producing offspring about five hundred times. Mollusks lay their eggs on the leaves of plants. Incubation occurs within 14-20 days. The eggs hatch into thin-shelled babies. Thus, pond snails, in addition to being very voracious, are also prolific. Therefore, the question of their breeding among aquarists is not worth it. More often another problem arises - how to prevent their frequent reproduction and overpopulation of the aquarium. If the task is to breed these mollusks, then you can stimulate the breeding process by raising the water temperature by a couple of degrees.

Did you know? The largest sea snail is considered to be the giant Australian trumpeter, whose shell reaches 91 cm and weighs 18 kg. The tiger Achatina is recognized as the largest land mollusk - with a shell 27.5 cm high and weighing about 1 kg.

Snails do not have to be planted in the aquarium themselves. They may appear unexpectedly - their eggs are brought along with underwater plants. In this case, the owner needs to organize their proper maintenance and ensure that the number of individuals does not exceed the capacity of the aquarium tank. If it is possible to control their reproduction, then the presence of pond snails will certainly benefit the fish dwelling - they can help get rid of unfriendly algae that settle on the decor, walls and plants, and keep their place of residence clean. Shellfish are indispensable cleaners for spawning aquariums. Overpopulation by snails threatens with oxygen deficiency, because of which, first of all, the fish will suffer.

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The large pond snail is a typical representative of freshwater. In our article, we will consider the living conditions and typical structural features of this animal.

Mollusks: organization features

Translated from Latin, the name of this type of animal means "soft-bodied". Some of them have shells. But in any case, the body of these invertebrates is soft and unsegmented. You can meet them in fresh and salt water. So, toothless and barley live in ponds and lakes, and mussels and octopuses live in the seas. Snails and slugs can be found in wet areas of land.

In the body of mollusks, three parts can be distinguished: the head, trunk and leg. Most of them move quite slowly, since the muscles are represented by separate bundles. In all mollusks, the body is surrounded by a fold of skin, which is called the mantle.

Basics of classification

Depending on the structural features, three classes of molluscs are distinguished. A characteristic feature of cephalopods is the modification of the legs into tentacles. They are located around the mouth. On the tentacles are suction cups, with the help of which animals catch and hold prey. Cephalopods are capable of jet propulsion due to a special tubular formation - a funnel. Representatives of this class are squids, cuttlefish and octopuses.

There are barley, mussels, mussels and oysters. All of them have a body consisting of a trunk and legs, as well as a shell of two valves. The large pond snail is a representative of gastropod molluscs. Let us dwell on its structure in more detail.

Large pond snail - a representative of gastropod mollusks

Large, or found in fresh waters rich in vegetation. His body, like all gastropods, consists of a head, torso and legs. The middle part is completely located inside a spirally twisted shell, consisting of lime covered with a layer of horn-like substance. This is a kind of dwelling and shelter. The shell of a large pond snail is spirally twisted. The maximum is 4-5 turns. It has a hole called a mouth. Through it, the head and leg are drawn inward. The shell of a large pond snail and a horn coil is closed with a special lid in case of danger. This structure is an additional defense against enemies.

The structure of a large pond

Why are the mollusks represented by the pond snail called gastropods? It's all about the structure of their body. There are no clear boundaries between its parts. The leg is a flat and muscular protrusion that completely occupies the abdominal part of the body. Its surface exudes mucus, which provides easy sliding on various substrates and water film.

The pond snail has a pair of tentacles. This If you touch them, the mollusk will pull its head inside the shell. The eyes are located at the base of the tentacles. The pond snails also have organs of balance. They are represented by small bubbles, inside of which special bodies are located. Changing the position of these structures keeps the mollusc in balance.

Circulatory and respiratory systems

The large pond snail has a type. It consists of a two-chambered heart and vascular system. The blood mixes with the abdominal fluid, washing all tissues and organs. From the heart, it enters the arteries, and in the opposite direction moves through the veins. Despite the fact that a large pond snail lives in water, it breathes exclusively atmospheric oxygen. To do this, the animal moves to the surface of the water and opens a breathing hole located at the edge of the shell to the outside. It leads to the lung, where the blood is enriched with oxygen.

Digestive and excretory systems

The big pond snail moves slowly but surely. Why does he constantly "travel"? The mollusk moves in search of food, scraping it from underwater objects with the help of its jaw and grater. The latter consists of several rows of horn teeth. The process of splitting nutrients is accelerated by the enzymes of the digestive glands - salivary and liver.

An anus opens above the head of the pond snail. And next to it, the duct of the urinary system opens. The latter is represented by a single kidney and an ureter with a hole.

Reproduction and development

According to the type of reproductive system, a large pond snail is a hermaphrodite. This means that both female and male sex cells are formed in his body. Fertilization in these molluscs is internal. As a result, sperm exchange occurs. Mollusks place zygotes in gelatinous cords, which are attached to underwater objects. As a result, young individuals with a thin shell develop.

So, to summarize: a large pond snail is a representative of gastropod mollusks. These are typical inhabitants of fresh water bodies. Pond snails have three body parts: the head, trunk and leg, as well as a spirally twisted shell.

Well, we got to the most controversial aquarium snail, namely the pond snail. I know that 99% of aquarists not only dislike them, but hate them with fierce hatred for their voracity and fertility. However, it is still worth talking about the pond snail (more precisely, pond snails).

A bit of biology

Pond snails are a family of snails from the Pulmonata order, which, according to different classifications, includes from one (Lymnaea) to two (Aenigmomphiscola and Omphiscola) or several genera (Galba, Lymnaea, Myxas, Radix, Stagnicola), which differ mainly in the structure of the reproductive system. In appearance (by shells), representatives of these genera differ little from each other. In our review, we provide descriptions of the seven most common types of pond snails in central Russia. To avoid confusion, we indicate their species names according to the traditional classification, according to which all pond snails belong to the same genus Lymnaea. However, in the description of individual species, information is provided on modern views on their taxonomy, along with their new names.

All pond snails have a well-developed shell spirally twisted to the right (see how to determine the twist) by 2-7 turns (see photos and drawings). In different types of pond snails, it is of different sizes and shapes - from almost spherical to highly conical, with a more or less high curl, with a very extended last whorl. Most are light horn, horn, brownish horn, brownish brown, or black brown. Most often, it is thin-walled, slightly transparent and more matte, tower-shaped or ear-shaped; the mantle almost does not emerge from the mouth.
The body of pond snails is right-handed, thick, their head is wide, transversely cut; respiratory and genital opening on the right side. The visceral sac is in the form of a conical spiral. The tentacles are flat, triangular in shape, short and wide. The leg is rather long and massive. Its sole is elongated-oval. There is a short siphon formed by the outer edge of the mantle.
The pharynx of the pond snail is a muscular sac that passes into the esophagus, then into the goiter and stomach; the latter consists of a bilobed muscular section and an elongated pyloric section; a muscular stomach is characterized by a rough structure and contributes to the crushing of captured food; in the pyloric stomach and in the intestine leaving it, food is digested; the anus opens at the mouth of the shell.

When observing a pond snail in an aquarium, one can see how it sticks out the front part of the body from the shell and slowly slides along the glass walls. In this protruding part of the body, one can distinguish the head, clearly separated from the rest of the body by the neck interception, and the leg, a large muscular organ of movement of the pond snail, occupying the entire abdominal part of its body. On the head are triangular movable tentacles, at the base of which eyes sit; on the ventral side of the head in its front part, a mouth gap is placed. The movements of pond snails are of three types - sliding along surfaces with the help of the foot, ascent and immersion due to the lung cavity, and sliding from below along the surface film of water.
The movement of the pond snail along underwater surfaces can be well traced when it crawls along the glass wall of the aquarium. It is caused by muscular contractions, undulating and evenly running along the sole; these movements have a fine adaptability, which allows the mollusk to move along thin twigs and leaves of aquatic plants.
Ascent to the surface and immersion to the bottom is carried out due to the filling and emptying of the lung cavity. With the expansion of the cavity, the cochlea floats to the surface without any push along a vertical line. For an emergency dive (for example, in case of danger), the pond snail pushes out the air in the lung cavity and falls sharply to the bottom. So, for example, if you prick the tender body of a mollusk floating on the surface, then the leg will immediately be drawn into the shell, and air bubbles will escape through the respiratory hole - the pond snail will throw out all its air ballast. After that, the mollusk will drop sharply to the bottom and will no longer be able to rise to the surface otherwise than by crawling along underwater surfaces, due to the loss of its air float.
The third way of movement is sliding along the lower surface of the water. When surfacing, the pond snail touches the surface tension film with the sole of the foot, then abundantly secretes mucus, straightens the leg, slightly arching the sole inward in the form of a boat and, contracting the muscles of the sole, slides over the surface tension film covered with a thin layer of mucus.

Like other lung snails, pond snails lack primary gills and breathe atmospheric air with the help of a lung, a specialized section of the mantle cavity, which is adjacent to a dense network of blood vessels. In order to renew the air in the lung cavity, they periodically rise to the surface of the water. Having risen to the surface, the pond snail opens its respiratory opening, which is located on the side of the body, near the edge of the shell, and air is drawn into the vast lung cavity. At this time, you can hear a characteristic squelching sound - the "voice of a mollusk" - this is the opening of the respiratory hole leading to the mantle cavity. In a calm state, the respiratory opening is closed by the muscular edge of the mantle.
The frequency of lifting for breathing depends on the temperature of the water. In well-heated water at a temperature of 18°-20°, pond snails rise to the surface 7-9 times per hour. As the water temperature drops, they begin to rise to the surface less and less often and in autumn, long before the water body freezes at a temperature of 6 ° -8 ° C, due to a general drop in activity, they cease to rise to the surface at all. While the photosynthesis of aquatic plants continues, pond snails consume oxygen bubbles on plants for respiration, and then stop filling the mantle cavity with air. At the same time, it either subsides or fills with water - a paradoxical, rare fact in nature, when the same organ alternately functions either as gills or as a lung.
In addition to breathing air or water, flowing in the cavity of the lung, the pond snail also lives due to skin breathing, which is carried out by the entire surface of the body washed by water; at the same time, the cilia of the skin of the pond snail are of great importance, the continuous movement of which contributes to the change of water washing the surface of the body of the mollusk.

Prudoviks are omnivores, but in nature they prefer plant foods. Slowly crawling, they scrape off algae raids from various objects submerged in water, for example, from the surface of the stems and leaves of higher aquatic plants. If algae become scarce, they also consume living plants - leaves and stems of aquatic plants, choosing the most tender of them, as well as plant detritus.
To scrape food, pond snails use a toothed grater - a horny plate that fits in the pharynx on a tongue-like elevation. The plate of the grater from the surface is seated with rows of cloves. The nature of the grater is easy to observe in the aquarium, when the pond snail crawls over the glass and from time to time sticks the grater out of its mouth and runs it over the surface of the glass to scrape off the layer of green algae that has developed on it. Pond snails sometimes use animal food - they devour the corpses of tadpoles, newts, fish and mollusks, scraping them from the surface, small invertebrate animals.
Lifestyle. At the height of summer, pond snails stay near the surface of the reservoir, and sometimes even on the very surface of the water. To catch them, there is not even a need to use a net, they can easily be removed from underwater objects by hand.
When water bodies inhabited by pond snails, such as small lakes, ditches and puddles, dry out, not all mollusks die. When unfavorable conditions occur, mollusks secrete a dense film that closes the shell opening. Some can tolerate being out of the water for quite a long time.

Prudoviki, like other pulmonary gastropods, are hermaphrodites. Eggs and spermatozoa develop in the same organism, in different parts of the same gland, but after leaving it, the paths of the genital ducts are separated, and the male and female genital openings near the mouth of the shell open separately.
A muscular copulatory organ protrudes from the male genital pore during copulation, while the female genital pore leads to an extensive seminal receptacle. In pond snails, mating is observed, with one individual playing the role of a female and the other a male, or both mollusks mutually fertilize each other. Sometimes chains of copulating pond snails are formed, with the extreme individuals playing the role of a female or male, and the middle ones - both.
Egg laying continues throughout the warm season, starting in early spring, and in the aquarium in winter. The eggs of pond snails in the laid state are connected by a common mucous membrane. In an ordinary pond snail (Lymnaea stagnalis), the clutch looks like a transparent gelatinous sausage with rounded ends, which mollusks lay on aquatic plants or other objects (video). In this species, the length of the roller reaches 45-55 mm with a width of 7-8 mm; eggs in it 110-120.
Large pond snails are especially prolific. According to observations in the aquarium, one pair of pond snails produced 68 clutches in 15 months, and in the other, 168 clutches in 13 months. The number of eggs in a clutch varies by species.
After 20 days, tiny snails emerge from the eggs, already equipped with a shell, which grow quite quickly, eating plant foods.

Representatives of some species of pond snails living in the deep lakes of Switzerland have adapted to live at great depths. Under these conditions, they are no longer able to rise to the surface to capture atmospheric air, their lung cavity is filled with water, and gas exchange occurs directly through it. This is possible only in clean, oxygen-rich water. Such mollusks, as a rule, are smaller than their counterparts living in shallow water.
- The shape of the common pond snail shell depends on the place of existence of a particular individual. These mollusks are extremely variable; not only their size, color, shape, but also the thickness of the shell vary.
- Shells of all European types of pond snails are twisted to the right. Only as an exception are individuals with left-handed (leotropic) shells.
- The number of eggs in a clutch, as well as the size of the egg cord, varies widely. Sometimes in one clutch you can count up to 275 eggs.
- A large pond is quite demanding on the oxygen regime. At a high level of oxygen saturation (10–12 mg/l), mollusk populations are characterized by a high population density. Very rarely, L. stagnalis was found in oxygen-deficient water bodies.

Interestingly, pond snails can breed far before reaching their maximum age and size. For example, an ordinary pond snail becomes sexually mature already at the end of the first year of its life, when it grows only to half its normal size.
- Pond snails can reproduce even being isolated from other individuals, so that copulation is not an act necessary for them to continue life, reproduction may well occur through self-fertilization.
- Pond snails are used in neurophysiology as model objects for studying the functioning of the nervous system of animals. The fact is that the nervous system of pond snails includes giant neurons. Placed in a nutrient medium, isolated pond snail neurons are able to stay alive for several weeks. The arrangement of giant neurons in the ganglia of the pond snail is fairly stable. This allows the identification of individual neurons and the study of their individual properties, which differ significantly from cell to cell. Irritation in the experiment of a single ganglion cell can cause a complex sequence of coordinated animal movements. This may indicate that giant mollusk neurons are capable of performing functions that in other animals are performed by large, complexly organized structures of many neurons.
- Snails have no hearing and voice, very poor eyesight, but their sense of smell is well developed - they are able to smell food at a distance of about two meters from them. The receptors are located on their horns.
- To improve digestion, the pond snail absorbs sand from the bottom of the reservoir
- Lifespan: 3-4 years.
- Maximum crawling speed - 20 cm/min.
- A large pond snail (L. stagnalis), when the reservoir dries up, releases a dense film that closes the shell opening. Some of the most adaptable forms of molluscs tolerate being out of water for quite a long time. So, an ordinary pond snail lives without water for up to two weeks.
- When water bodies freeze, mollusks do not die, freezing into ice, and come to life when thawed.
- Based on the results of recent joint research by scientists from the Pedagogical University of Tula and the Institute of Developmental Biology of the Russian Academy of Sciences, new, very interesting facts about the life of mollusks were discovered. As it turned out, snails have the ability to communicate with each other, transmit important information to each other, and even “give parental instructions” to larvae that have not yet been born, but are in laid eggs. Although ordinary gastropod mollusks were chosen for the role of the test subjects - a coil and a large pond snail, scientists have an assumption that absolutely all representatives of the invertebrate world use this method of communication. At the first stage of the experiment, the experimental pond snails were divided into two groups. One of them was given food in the usual volumes, and the second was completely deprived of food for three days. Then water samples were taken from the containers in which the mollusks were kept, and from each container separately. As a result of the analysis, it was found that its chemical composition differs significantly from each other. Then the caviar previously laid by the snails was placed in both containers. In the third, control container, caviar was also placed, but it was filled with clean water. All this was left for 10 days, after which the results were compared. As it turned out, in clean water, as well as in the one where well-fed snails lived, the larvae managed to reach the stage of full formation. The situation was completely different in the water where the hungry snails lived - the development of the larvae almost completely slowed down. This fact was commented on by Elena Voronezhskaya, Doctor of Biological Sciences, she said that parents seemed to warn their children not to rush to develop and hatch, as they would not have anything to eat. In the course of further experiments, the following pattern was discovered: the longer the fasting period of adult snails, the more they released into the water a special substance that inhibited the development of larvae. This substance has received the name "RED-factor" from scientists, according to their assumptions, it is a lipoprotein.
- In a pond snail, most of the liver is located in the last turns of the spiral.
- One of the forms of the pond snail has adapted to life in hot springs near Baikal - the elongated pond snail (Lymnaea peregra)
- Biologists drew attention to the large size and yellow-orange color of the nerve cells of the brain of a large pond snail, well adapted to a polluted environment. These cells are colored by pigments known as carotenoids. They can accumulate oxygen and, if it is not enough in the external environment, use the stored one.
- The blood of an ordinary pond snail is not red, like that of coils, but bluish, because it is colored with copper-containing hemocyanin.

While the news number for 07/25/18 was being made up. Scientists from the Federal Research Center for Comprehensive Study of the Arctic of the Russian Academy of Sciences (FICKIA RAS) and the Northern Arctic Federal University (Arkhangelsk) have created a genetic catalog of pond snails. For pond snails, their taxonomy was unclear, and we applied the molecular genetic method to Old World pond snails, examining material from about 40 countries. We conducted a revision, during which we showed that pond snails are divided into 10 genera, including a genus new to science and two species of pond snails discovered in remote high-mountainous regions of the Tibetan plateau. The genus is named Tibetoradix, and the species are Makhrov's pond snail (Radixmakhrovi) and the Tibetan Kozlov's pond snail (Tibetoradixkozlovi) in honor of the outstanding modern Russian ichthyologist Alexander Makhrov, as well as the traveler and explorer of Central and East Asia Pyotr Kozlov, who lived in the 19th-20th centuries .. It turned out that that 35 species of pond snails live in the countries of Europe, Asia and Africa. "Before, grades ranged from three, ten or more"

And as usual, for those too lazy to read

Pond snails (Lymnaea stagnalis) belong to the class of gastropods, a subclass of true snails and a detachment of pulmonary mollusks (Pulmonata). Currently, there are about 120 species. The pond snail and other species of this family are very variable: the configuration, size, and thickness of the shell, and the color of the legs and torso of these organisms vary. They live in fresh water rivers, lakes and ponds. Ponds are equipped with a solid shell with a sharp top, twisted in 4 - 5 turns, and a large mouth, from which the head and leg protrude. The head is equipped with a mouth, two tentacles and two eyes. The body of the pond snail is a large spiral sac covered with a mantle and shell, and located above the leg. Bilateral symmetry is broken in the pond snail due to the turbospiral shape of the shell, which led to the asymmetry of the organs located in the mantle cavity (one atrium, one kidney, half of the liver). On the ventral side of the pond snail is a massive muscular leg with a wide sole, which serves to move it.

Structure

Pond snails, like other lung snails, lack primary gills. They breathe with the help of the lung, which is a specialized section of the mantle cavity, enriched with a large number of blood vessels. Pond snails periodically rise to the surface of the water surface to fill the lung with atmospheric air through a round breathing hole located at the base of the shell, since they can stay under water for no more than an hour. In addition, pond snails are able to breathe the entire surface of the body. In clean reservoirs, in oxygen-enriched water, mollusks can live at a depth and not rise for a new portion of oxygen. They get their oxygen from the water that fills the lung, which functions like a gill. Inhabited in such conditions, mollusks are smaller than those that live in shallow water. The heart is located next to the lung and consists of an atrium and a ventricle. Pond snails have an open circulatory system with colorless blood. The excretory organ is one kidney.

The nervous system is a near-pharyngeal nerve ring formed by nerve nodes, from which nerves extend to all organs. The tentacles are equipped with tactile receptors and chemical sense organs (taste and smell). There are also organs of balance.

The digestive system of the pond snail consists of the esophagus, sac-like stomach, liver, intestines and ends with the anus. The oral cavity of the pond snail passes into a muscular pharynx, in which a grater tongue (radula) is located, covered with rows of hard teeth. With a radula, the pond snail scrapes off particles of plants and small animals and eats them.

Pond snails feed mainly on plant foods. Their diet includes both living plants and decomposed ones. In addition, they eat bacteria and animal food (flies that have fallen into the water, fish eggs).