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Prudovik ordinary. Aquarium snail - pond snail

In Russia and Europe, there are different types of pond snails. Among them, the largest is the common pond snail, the shell of which can reach 7 centimeters. All species breathe with lungs, therefore, from time to time they are forced to swim to the surface. You can often observe how the pond snail, the photo of which is presented in this article, slides smoothly and slowly along the lower part of the surface water film, picking up oxygen from the air.

If the mollusks, “suspended” in this way, are somehow disturbed, they immediately release an air bubble from the respiratory hole and fall like a stone to the bottom. The eared pond snail is the closest relative of the common one. Its shell reaches 2.5 centimeters, which depends on the abundance of food and the temperature in its reservoir.

The common pond snail and other species of its family (in addition to those listed above, in our reservoirs you can find ovoid, small and marsh) are very variable. In this case, the shapes, sizes, thickness of the shell, color of the body and legs of snails vary. Along with those that have a strong shell, there are species with a very fragile, thin shell that breaks even with the slightest pressure. There can also be various forms of a curl and mouth. The color of the body and legs varies from sandy yellow to blue-black.

Structure

The body of the mollusk is enclosed in a spirally twisted shell, which has a mouth and a sharp top. The shell of the common pond snail is covered with a lime layer of a horn-like greenish-brown substance. It is a reliable protection of his soft body.

In the body of a snail, 3 main parts can be distinguished: the leg, head and body - although there are no sharp boundaries between them. Only the front part of the body, leg and head can protrude from the shell through the mouth. The leg is very muscular. It occupies the abdominal area. Such snails are called gastropods. At the same time, sliding on objects with the sole of the foot or hanging to the lower film of water, the mollusk smoothly moves forward.

The body at the same time copies the shape of the shell, adjoining it very closely. It is covered in the front part by a mantle (a special fold). The space between it and the body is called the mantle cavity. The torso in front passes into the head, which has a mouth on the underside, and two sensitive tentacles on the sides. A pond snail, when lightly touched, instantly draws its leg and head into the shell. Near the bases of the tentacles there is one eye each.

Circulation

The common pond structure has a rather interesting structure. So, he has a heart, which pushes the blood into the vessels. In this case, large vessels are subdivided into small ones. And from them already the blood goes into the gaps between the organs. Such a system is called "unclosed". Interestingly, the blood washes each of the organs. Then she again gathers in the vessels that lead to the lung, after which she goes directly to the heart. In such a system, it is much more difficult to ensure the movement of blood than in a closed one, since it slows down between organs.

Breath

Despite the fact that the snail lives in water, it breathes atmospheric air. To do this, the common pond snail, the structure of which is described in this article, floats to the surface of the reservoir and opens a round breathing hole at the edge of the shell. It leads to the lung - a special pocket of the mantle. The walls of the lung are densely braided. In this place, carbon dioxide is released and the blood is enriched with oxygen.

Nervous system

This mollusk has a near-pharyngeal concentration. From them, the nerves extend to all organs.

Food

The snail's mouth leads to the pharynx. There is a muscular tongue covered with teeth ─ the so-called grater. The common pond snail, the photo of which can be viewed in this article, scrapes off plaque from all kinds of microorganisms that form on various underwater objects, and also rubs various parts of plants. Food from the pharynx travels to the stomach and then to the intestines. The liver also aids in its digestion. In this case, the intestine opens with an anus into the cavity of the mantle.

movements

If the caught pond snail is put in a jar, it immediately begins to actively crawl along its walls. At the same time, a wide leg extends from the shell opening, which serves for crawling, as well as a head with two long tentacles. By sticking the sole of the foot to various objects, the snail glides forward. In this case, sliding is achieved by wave-like, smooth contractions of the muscles, which can be easily observed through the glass of the vessel. Interestingly, the common pond snail can wander along the lower surface of the water, as we have already discussed above. At the same time, it leaves a thin tape of mucus. It stretches across the surface of the water. It is believed that snails moving in this way use liquids, hanging from below to an elastic film that forms on the surface due to this tension.

Such crawling can be easily observed on the calm surface of the reservoir, going on an excursion or relaxing in nature.

If the pond mollusk, crawling in this way, again plunges into the water under a little pressure, it will be seen how it again, like a cork, rises to the surface. This phenomenon is easily explained: there is air inside the respiratory cavity. He supports the cochlea as the Prudovik can compress his respiratory cavity arbitrarily. In this case, the mollusk becomes heavier, therefore, sinks to the very bottom. But when the cavity expands, it floats to the surface along a vertical line without any push.

Try to immerse a pond snail floating on the surface of a reservoir in water and disturb its soft body with a touch of tweezers or a stick. The leg will immediately pull back into the shell, and air bubbles will come out through the breathing hole. Further, the mollusk will fall to the bottom and will not be able to independently rise to the surface in any other way than climbing on plants, due to the loss of the air float.

reproduction

The pond snail mollusk is a hermaphrodite, although its fertilization is cross. The snail lays eggs that are enclosed in slimy, transparent cords attached to algae. Eggs hatch into small pond snails with very thin shells.

If you still decide to start an ordinary pond snail, then you need to understand that a water temperature of about 22 ˚С and its moderate hardness are considered a prerequisite for its maintenance.

In this article, we will consider who a pond snail is, what features it has, where it is found, and much more about this wonderful mollusk. What types of pond snails exist and what do they look like.

Any from pond snails, whether ordinary, small or large, is a snail that lives in ponds and gardens where there is enough moisture.

Large and small pond

The large pond snail belongs to the class of gastropods, which is the most numerous and diverse in comparison with other classes of gastropods. There are more than 90 thousand species of such mollusks in nature, and their habitat is not only ponds, but also the sea and land.

The large pond snail is about 5 cm long and has many distinctive features from the brothers.

Let's talk about the external structure of a large pond snail. It consists of three parts that are noticeable and perfectly distinguishable from each other. The body outside the shell is covered with a mantle to protect the internal mucosa, the shell of a mollusk is twisted for convenience in a spiral of 5 turns. This structure of the shell provides reliable protection of the body from irritants, mechanical damage. . The sink contains lime for the basis of the structure of spirals, and on top of it is covered with an organic substance of a horn-like type (such is on the horns of cattle, etc.).

Due to the structure of the shell, he received an asymmetric body for better accommodation in the "protection", the connection of the shell with the body is carried out due to the muscle. The muscle ensures that the animal is drawn into the shell, and with the help of a pronounced leg, the mollusk can crawl back.

In the internal structure pond snails of any type, everything is arranged simply. The main organs are:

  1. digestive complex;
  2. leg;
  3. eyes;
  4. excretory and respiratory system;
  5. sole and mucus secretion glands.

The snail feeds on plant food in a crushed form, then food from the tongue (has a “grater”) passes into the throat, is processed by the secretion of splitting and processed in the stomach and intestines.

The circulatory system is open, and the molluscs move due to the powerful leg, which glides over any surface thanks to the secret secreted by the glands.

These animals are unique and do not need to be killed. . They don't harm a person, nor gardens, because they feed on plant foods that are easily processed (that is, weeds such as ephemera (wheatgrass, wood lice). Also, snails have healing properties, when properly fed and used, they secrete mucus that nourishes human skin and regenerates epithelial cells .

Small pond snail

Who are the puddlers in general, you know from the previous paragraphs, now we will talk about small things. In nature, there are several small pond snails:

Small snails are in all gardens are small in size and beautiful in appearance. Be supportive of snails, they do no harm, more good.

common pond snail

There is an ordinary pond snail in the middle lane - Russia, Europe. The pond snail has a large size, one shell is 7 cm, not including the body. The pond snail breathes with nothing more than miniature lungs, the circulatory system is not closed, they feed on hard plant foods, detritus and midges. The external structure does not differ from a large pond snail, except that the body does not always correspond to the size of the shell, sometimes smaller than the shell. Shell color - mother-of-pearl, brown. Body color - brown, gray, white.

Snails can easily survive both in nature and in the artificially created environment of a terrarium, aquarium. The snail moves thanks to the secretion of mucus and the outer sole, which allows it to move quickly enough over various distances. Snail mucus is rarely used in cosmetology, but most often the mollusk is kept for decoration.

Mollusks are attached to people - breeders, so if you fell in love with a snail, then do not give it to others, otherwise the weak heart of the animal will not stand it.

And now let's take a look at the photo of the pond

Snails big pond

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 a foot, ascent and immersion due to the pulmonary 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 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 work of the grater is easy to observe in the aquarium, when the pond snail crawls along the glass and from time to time sticks the grater out of its mouth and runs it over the surface of the glass in order 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 come out of 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, transfer important information to each other, and even “give parental instructions” to larvae that have not yet been born, but are in the 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 the 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

In ponds, lakes and quiet backwaters of rivers on aquatic plants, you can always find a large gastropod snail - common pond snail.

Structure

The body of the pond snail (Fig. 58) is enclosed in a shell spirally twisted in 4-5 turns, which has a sharp top and a large opening - the mouth. The shell of wine consists of lime, covered with a layer of greenish-brown horn-like substance and reaches a height of 45-55 mm. It serves as protection for the soft body of the pond.

In the body of a pond snail, three main parts can be distinguished: the torso, head and leg, but there are no sharp boundaries between them. Only the head, leg and front part of the body can protrude from the shell through the mouth. The leg is muscular and occupies the entire ventral side of the body. Molluskshaving legs like those of a pond snail are called gastropods.

The sole of the foot secretes mucus, with the help of which the foot slides over underwater objects or even over the surface film of water, hanging from below, the pond snail moves smoothly forward.

The body repeats the shape of the shell, closely adjacent to it. In the front part of the body is covered by a special fold - the mantle. The mantle (skin fold) and the shell, twisted in a spiral, form the cover of the pond snail. The space between the body and the mantle is called the mantle cavity, through which communication with the external environment is carried out. In front, the body passes into the head. A mouth is placed on the underside of the head, and two sensitive tentacles are placed on its sides. When touched, the pond snail quickly draws its head and leg into the shell. Near the bases of the tentacles is on the eye.

Digestive system

The common pond snail is a herbivore. The mouth leads to the throat. A muscular tongue covered with teeth is placed in it - this is the so-called grater. With it, the pond snail scrapes off plaque from organic matterformed on underwater objects, or scrapes the soft parts of plants. In the pharynx, food is processed by the secretions of the salivary glands. From the pharynx, food enters the stomach, then into the intestines. Digestion of food is also facilitated by a special digestive gland - the liver. The intestine ends with an anus located above the head.

Respiratory system

Although the pond snail lives in water, it breathes atmospheric air. For breathing, it rises to the surface of the water and opens a round breathing hole at the edge of the shell (Fig. 58), through which atmospheric air enters. It leads into the cavity - the lung, formed by the mantle and penetrated by a network of blood capillaries. In the lung, the blood is enriched with oxygen and carbon dioxide is released.

Circulatory system

The circulatory system of the pond snail (Fig. 58) is represented by a two-chamber heart, consisting of an atrium and a ventricle, and blood vessels.

Arterial blood enters from the lung into the atrium, then into the ventricle, and from it moves through the vessels to all organs of the body and pours out between them. Such a circulatory system is called open. Having given up oxygen and enriched with carbon dioxide, the blood is collected in the venous blood vessels and enters the lung, where gas exchange again takes place. Oxygenated blood travels through the vessels to the heart. It is more difficult to ensure the movement of blood in an open circulatory system than in a closed one, since the movement of blood slows down in the spaces between the organs. The voluminous two-chambered heart serves as a pump that pumps blood.

excretory system

The excretory system of the common pond snail (Fig. 58) includes one kidney with a ureter that breaks off near the anus.

The kidney has a direct connection with the circulatory system and absorbs the end products of the breakdown of protein substances from the blood.

Nervous system

The nervous system of the pond snail is of the nodal type and includes a near-pharyngeal nerve ring formed by two nodes and four pairs of nodes with nerves extending from them. material from the site

sense organs

The pond snail has organs of vision under the tentacles - eyes, organs of touch - tentacles and organs of balance - small whitish bubbles lying on the surface of the nerve node of the legs. In these bubbles in a liquid medium are small bodies, changing the position of which allows you to maintain the balance of the body.

reproduction

Reproduction is sexual. Common pond snails are hermaphrodites. Fertilization is internal.

During the copulation of two individuals, mutual fertilization takes place, that is, the exchange of male gametes - spermatozoa. After that, the individuals disperse and lay fertilized eggs tied into gelatinous cords. They attach themselves to underwater plants.

From the zygote develop small pond snails with a thin shell.

Position in systematics (classification)

The common pond snail is one of the species of the most numerous class among mollusks - Gastropods.

On this page, material on the topics:

  • Message about the pond snail briefly

  • Does the common pond snail secrete mucus

  • Type of circulatory system in a pond snail

  • Adaptation of mollusks to the habitat common pond snail

  • Grater at the pond

Questions about this item:

  • From early spring to late autumn, snails from a large family of pond snails can be found in stagnant and slowly flowing reservoirs. The common pond snail is the largest of the common ones.

    More than 100 species of this family are known, and we have several dozen species, most of which belong to the genus of pond snails. The common pond snail, or lake snail, is the most common and widespread in Africa, North America, Europe and North Asia up to Kamchatka.

    LIVING GUTTLER

    The appearance of the pond snail is very variable: depending on the conditions of existence, the color, shape and size of the shell and body vary. In this regard, several geographical subspecies are distinguished.

    Prudoviks are common inhabitants of ponds, lakes, backwaters of rivers, canals and other bodies of water with abundant vegetation. They thrive even in brackish water. These are large gluttons, eating both living and rotting plants, and sometimes insects and fish eggs that have fallen into the water.

    The mollusk spends most of its life crawling among the thickets at a speed of 30 cm to 1 m per hour and scraping algae and small animals from the underside of the leaves.

    To do this, he has a special device in his oral cavity - a grater, or radula. It is a tongue with many sharp horny teeth. Sometimes pond snails swallow sand, which, remaining in the stomach, helps to digest food.

    Ordinary pond snails can also be found in swamps and puddles with rather dirty water, although they do not live in rotting water. Snails can survive without water for up to two weeks if their pond is dry. In this case, they have mucus hardening in the air, which, like a lid, securely seals the shell with the host drawn into it.

    And there is no real lid, like some mollusks, in lakers. Even after spending some time frozen in the ice, after thawing, the pond snail can come to life.

    FOOT UP

    A long time ago, the aquatic ancestors of the pond snails breathed with gills, and then went out onto land and acquired lungs, more precisely, an unpaired lung - a respiratory cavity formed by a fold of skin. Later, they returned to an aquatic lifestyle, but did not change their lung breathing. Periodically, usually 6-9 times per hour, pond snails rise to the surface to renew the air in the lung cavity, and expose the muscular edge of the mantle, rolled into a tube, forming a breathing hole on the side, near the edge of the shell. But if necessary, the pond snail may not rise to the surface for quite a long time, about an hour, saving air. Pulmonary respiration is partly replaced by skin respiration. Having risen to take a sip of air, the snails slowly crawl along the underside of the surface film of water, leaving behind a slimy trail. This is possible thanks to the wide sole and air-filled respiratory cavity. If such a snail is pushed, it, immersed in water, rises again like a float. But the mollusk can also compress the lung, releasing an air bubble, if it wants to dive deeper.

    CRADLE FOR SNAIL

    Like all gastropods, the common pond snail is a hermaphrodite, that is, each individual has both female and male genital organs. But he has cross fertilization. In order to lay viable eggs, pond snails mate from early spring to late autumn, except during the frosty winter months, which they spend in a state of torpor at the bottom of a pond. Eggs dressed in a double shell (from 20 to 130 pieces) are immersed in a mucous mass and suspended from the wall of the capsule or cocoon surrounding them. In general, this design looks like a transparent slimy cord attached to underwater objects. Each egg in such a cord is protected and provided with protein material for the development of the embryo. Perhaps this way of caring for offspring was inherited by pond snails from their land ancestors, for whom it was important that the eggs do not dry out. After 20 days, small snails with a thin shell emerge from the eggs, which grow quite quickly, eating plant foods, and at the end of the first year of life they are ready to become parents themselves, although they still reach only half of their normal size.

    Representatives of some species of pond snails living in deep lakes 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.

    A BRIEF DESCRIPTION OF

    Type: shellfish.
    Class: gastropods.
    Family: pond snails.
    Genus: pond snails.
    View: ordinary, or large, pond, or lake.
    Latin name: Limnaea stagnalis .
    Size: shell length - 68-70 mm, width - 27 mm.
    Coloration: shell brown, brown, leg and body from blue-black to sandy-yellow.
    Life expectancy of a pond snail: on average about a year, up to 2 years.

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