Common pond snail is a group of animals. Aquarium snail - pond. Circulatory and respiratory systems

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

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 extends 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 it were, suspended from the wall of the cocoon. The complex structure of the egg clutch is also characteristic of other freshwater lung mollusks. 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 pond snail eggs were inherited from 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 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.

Every beginner in the aquarium business after a while is faced with the fact that the water becomes cloudy, and aquatic plants begin to grow uncontrollably. Cleaning an aquarium and putting it in order takes a lot of time. But you can get helpers - one of them is a pond snail. She is a natural cleaner of walls and aquarium accessories. In addition, it is interesting to watch snails no less than fish.

Appearance and structure of the pond snail

Lymnaeidae is the Latin name for the pond snail. They live in fresh stagnant water or in ponds with a slow current.

The common pond snail has a fine-spiral shell with 5-6 whorls, usually twisted to the right. Species with left-handed shells are found only in New Zealand and the Sandwich Islands. The degree of its elongation depends on the current in this particular reservoir - the width can be 0.3-3.5 cm, it is from 1 to 6 cm high. There is a large hole in the front of the shell.

The color of the pond snail depends on the natural features of the habitat. Most often, shells are in a brown palette. And the head and body are yellowish-brown to blue-black.

The body of the mollusk consists of three sections - the head, trunk and legs. All these parts are tightly attached to the inner surface of the shell. The head of the snail is large, on the head there are flat triangular tentacles, on the edges of them on the inside there are eyes.

The mollusk breathes through a hole protected by a noticeably prominent blade.

Habitats

The pond snail is found in Europe, Asia, North America and North Africa. In addition to fresh stagnant waters and slow-flowing reservoirs, they are found in slightly saline and saline waters, as well as in geysers. In Tibet, they live at an altitude of 5.5 thousand meters and a depth of 250 meters.

Varieties of the pond snail

The species differ in the shell color characteristic of each locality, the thickness of its walls, the shape of the rings and mouth, and the color of the legs and body.

The common pond snail (or large pond snail) is the most common species in the gastropod mollusk family. The length of the shell, which has a conical shape, is 4.5-6 cm, it is 2-3.5 cm wide. The shell spiral has 4-5 rings, which expand significantly with each turn, ending with an impressive hole. The color of the translucent walls is brown. The body is greenish-brown. This species ubiquitously inhabits freshwater reservoirs of the countries of the Northern Hemisphere.

The small pond snail (it is also called the truncated pond snail) has an elongated, pointed shell with 6-7 whorls. The coils of the rings are twisted to the right side. The shell walls are thin, but strong, whitish-yellow, almost transparent. It is 1-1.2 cm long, 0.3-0.5 cm wide. The body color is white-gray, uniform, but dark spots are possible on the mantle. This species is widespread in the nature of Russia, inhabits swampy reservoirs and ponds. Sometimes found in low water in drying up reservoirs.

In the auricular species, the shell opening resembles a human ear - hence the name of this variety. The shell is from 2.5 to 3.5 cm in height, 2.5 cm in width. Its walls are thin, the color is gray-yellow. This mollusk has no more than 4 shell rings. The shell has an almost round appearance, since the last whorl is rather large in diameter compared to others. The body is yellowish-green and grayish-green with many speckles. The mantle is gray or spotted. It is found in reservoirs with different composition of water. Lives on rocks, sunken tree trunks, stems and leaves of aquatic plants.

Other famous types of pond snail:

• frilled (cloaked man);
• oval (ovoid);
• marsh.

Habits in the wild and life expectancy

In their natural environment, pond snails feed mainly on plants. But sometimes they eat flies, fish eggs and other similar small aquatic animals.

To breathe, they get out of the water column to the very surface. A snail needs to rise at least 6-9 times a day. But for species that live at a considerable depth, oxygen dissolved in water is enough. The mollusk draws water into the lung cavity, turns upside down in the water and slightly draws it into the shell.

In nature, a pond snail can rarely be found sitting motionless on some snag. The mollusk is almost constantly busy - it scrapes algae from stones, eats aquatic vegetation. pond snail is about 20 cm / min.

Despite the fact that pond snails spend most of their lives in the water column, they survive well in dried-up reservoirs and in water covered with a crust of ice. The mollusk simply seals the shell with a film, and when moisture appears or thaws, it comes to life.

On average, in the wild, the life expectancy of a pond snail is only about 9 months. But with the right content, a pond snail in an aquarium can live up to 2 years.

Aquarium maintenance

Prudovik is a gluttonous mollusk. Therefore, it is better not to settle them in carefully grown chic homemade "herbalists" - you can lose all aquatic plants. Snails especially like soft plants with succulent stems and leaves. But in the content of the pond snail is unpretentious.

Basic conditions:

• Water temperature in the aquarium should be maintained at 20-26°C. In warmer water, the mollusk will actively multiply, which is undesirable in a small amount of water.
• Hardness of water - moderate, lighting - dim (optimally - a low-power fluorescent lamp).
• Aquarium volume anyone will do, the main thing is to control the population, not allowing pond snails to multiply endlessly. If there are too many individuals, diseases can develop.
• you need a rocky one - pebbles are best, but a coarse sandy bottom is also acceptable.
• They clean the aquarium with pond snails in the usual way, replacing a third of the water every 7 days. Filter you need a powerful one, the direction of the jet is preferably horizontal.

Before settling new pond snails, it is necessary to keep them in quarantine for several days. It is recommended to buy shellfish in pet stores. Since in the markets, snails can be freshly caught in the pond, and infect the entire aquarium with infections.

With whom you can live together in the same aquarium

Feeding at home

Prudoviki prefer plant foods. They do not need frequent additional feeding - algae, rotten plant parts and fish waste are enough to feed. All these remnants of molluscs, like a grater, are scraped off the walls and the ground with long, powerful tongues. You can also give them:

• fresh pumpkin,
• apples,
• zucchini,
• white cabbage,
• broccoli,
• tomatoes,
• carrot,
• greens grown in the country (cut everything into small pieces).

From time to time, pond snails need mineral supplements - calcium is needed for shells. It is found in chalk, egg shells, sepia - all this must be given in crushed form.

Breeding

Prudoviks are hermaphrodites. They breed both singly and in flocks. Caviar is laid several times during the year. That is, throughout life, offspring are bred from about 500 clutches. Egg clutches are attached to the leaves of plants.

The masonry consists of small transparent eggs fastened to each other with mucus, forming an oval-shaped pouch. If this is facilitated by favorable conditions of detention, one individual within 4 months makes up to 25 clutches of 80 eggs each.

The incubation period is 14-20 days. Newly hatched babies already have thin shells.

Sexually mature age in pond snails occurs at about 7 months.

Diseases

These snails are resistant to diseases, but they themselves are often carriers of infection (which is almost impossible to determine by eye). They themselves get sick with a fungus - visually this manifests itself in the form of a white coating on the sink. Therapy - regular baths with manganese and saline solutions, long-term quarantine.

How much does a pond snail cost

In order to avoid infections, it is better to purchase pond snails in specialized pet stores, and not from private traders, and not to catch them yourself in reservoirs. The average cost of one adult is about 50 rubles.

contact hazard

Many different snails live in reservoirs, rivers, gardens, but the most common species is the pond snail. It lives in places where there is enough moisture, so it can be seen all over the world. This mollusk is quite often settled in aquariums, as it copes remarkably with the plaque that forms on glass, stones or other objects, and it is also interesting to watch such a snail.

The pond snail copes remarkably with the plaque that forms on the glass of the aquarium.

Description of the mollusk

The pond snail is a freshwater snail that has a well-developed spiral shell. The shell itself consists of five or six turns. On one side, it has a mouth, and on the other, a sharp peak. It reliably protects the soft body of the snail from various adverse effects and mechanical damage.

The pond snail breathes with the help of lungs, and therefore it is forced to periodically rise to the surface of the water. At the very edge of the shell there is a special round hole that just leads to the lung. And it is there that the blood is enriched with oxygen and carbon dioxide is released.

The body of a pond snail consists of three main parts:

• heads;
• torso;
• legs.

The leg of a freshwater inhabitant occupies the abdominal part of the body. It is muscular, with its help the snail moves along the surface. The life cycle of mollusks is rather short, since in winter they all die. Depending on the species, pond snails differ from each other in the color of the shell, body and legs, and they may also have a different shape and thickness of the shell.

The most common types

Snails are unique animals that do not cause any harm to humans, on the contrary, they are of great benefit, as they actively eat various weeds, clean the aquarium well from build-up and even have healing properties. In nature, there are many variants of the pond snail, each of which has its own characteristics.

But the most common are the following types:

There are other types of these molluscs, but they are much rarer. For example, there are pond snails that live at a depth of up to 250 m or at an altitude of 5 thousand meters.

Nutrition and reproduction

A large pond snail feeds mainly on plant foods. In nature, it eats various weeds, algae and even rotten plants. In the aquarium, with the help of a long tongue, he scrapes off the plaque that forms on the walls. And this mollusk eats any food that settles on the bottom.

As additional feeding, small pieces of eggshell and chalk can be placed in the aquarium. From vegetable food, snails can be given an apple, cabbage, zucchini, pumpkin, carrots, lettuce.

In nature, the pond snail eats various weeds, algae and even rotten plants.

Prudoviki, like many other snails , are hermaphrodites, but their fertilization occurs in a cross way. And they are also able to independently fertilize their own eggs. These moisture lovers lay a large number of eggs at a time, which are enclosed in a special transparent mucous masonry. Usually it has an elongated shape and is attached to various underwater objects, most often to vegetation. Sometimes in one such clutch there are up to 300 eggs.

The eggs themselves are small and almost transparent. After about a month, small snails hatch from them, which, by external signs, are no different from adults. Pond snails reproduce quite actively, therefore, if they are in an aquarium, you need to periodically remove excess masonry. In captivity, these mollusks can live up to two years, and during this period they lay eggs up to 500 times.

Difficulties in maintenance and illness

The pond snails are completely unpretentious animals, but the main difficulty in keeping them is that they can carry dangerous diseases which are almost impossible to recognize at first glance. The most common disease in these mollusks is fungal infection. And if an infected individual is placed in a common aquarium with fish and other inhabitants, then it can quickly spread the infection.

To avoid such a situation, before planting a pond snail in a common aquarium, you need to keep it in quarantine for several days. During this period, you should put it daily for several minutes in a weak solution of potassium permanganate or table salt.

If the snail does not consume the right amount of minerals and trace elements, then the walls of its shell may begin to become damaged or thinner. In this case, the pond snail should begin to be fed with foods that contain a high content of calcium. After a while, the shell will overgrow and fully recover.

The shell is spirally twisted, without a lid. In some species (slugs), the shell is reduced. Ganglia are concentrated in the head section, forming a peripharyngeal nerve ring. A nerve branch departs from the right parietal ganglion to an additional unpaired ganglion. Pulmonary mollusks have one atrium, one lung, and one kidney.

rice. one.
A - top view, B - side view: 1 - mouth, 2 - cerebral ganglion, 3 - pleural ganglion,
4 - parietal ganglion, 5 - visceral ganglion, 6 - liver, 7 - pericardium, 8 - lung, 9 - heart, 10 - kidney, 11 - stomach, 12 - sex gland, 13 - mantle cavity, 14 - leg, 15 - head, 16 - anus, 17 - additional unpaired ganglion.

(Fig. 2) - one of the largest terrestrial mollusks in Europe. The spherical-twisted shell has 4-4.5 whorls, reaches a height of 5 cm, a width of 4.5 cm. The shell is usually yellowish-brown in color with dark brown stripes running along it. The color and width of the stripes vary. On the head of a grape snail there are two pairs of tentacles, on one of which there are eyes, the other serves as organs of smell and touch. It feeds on the green parts of plants. By eating the leaves and buds of the vine, it can harm vineyards.

rice. 2. Grape
snail (Helix pomatia).

Grape snail is a bisexual animal. It has one hermaphroditic gland, in which female and male gametes are formed. A hermaphroditic duct departs from the gland, into which the protein gland flows. After the confluence of the protein gland, the hermaphroditic duct expands, forming two grooves: a wide one for eggs and a narrow one for spermatozoa. Further, each of the gutters is converted into independent channels, respectively, the oviduct and the vas deferens. The oviduct flows into the uterus, the uterus into the vagina. In addition to the oviduct, the ducts of the seminal receptacle and bags with calcareous needles flow into the uterus. The vagina opens with a genital opening in a special skin invagination - the genital atrium. The vas deferens passes into the ejaculatory canal, penetrating the copulatory organ, which opens into the genital atrium. During mating, grape snails exchange spermatophores (packages of sperm), which are captured by the sperm receptacles. Fertilization will occur after mating. The eggs that enter the uterus are fertilized by foreign spermatozoa coming from the seminal receptacle. The formed eggs are laid in a mink, which the parent individual previously digs in the soil with its muscular leg.

In a number of European countries, grape snails are used for food.

rice. 3. Big
pond snail (Limnea stagnalis).

(Fig. 3) and small pond snail (L. truncatula)- often found inhabitants of our fresh water bodies. The head bears one pair of tentacles, at the base of which are eyes. Hermaphrodites. During mating, just like in a grape snail, sperm is exchanged, and the fertilization of eggs is carried out by foreign sperm. They lay their eggs in slimy cords that are attached to underwater plants and other objects. Development is direct, without a larval stage. They breathe atmospheric oxygen, so they periodically rise to the surface of the water in order to gain a portion of air.

The size of the shell, its shape, and the color of the legs and body are characterized by strong variability in the large pond snail. For example, the color of the torso and legs can vary from blue-black to sandy yellow. The length of the shell of a large pond snail can reach 7 cm. The large pond snail is omnivorous, it feeds not only on plants and small animals, but can eat dead plant remains and animal corpses.

rice. four.
A - arion rufus (Arion rufus),
B - limax maximus
(Limax maximus).

A composite group of terrestrial pulmonate mollusks with a partially or completely reduced shell (Fig. 4). On the head, next to the mouth opening, there is a pair of labial tentacles, on top of which are eye tentacles that carry eyes. The narrowed section of the body between the head and the mantle is called the "neck". On the bottom of the neck, a duct of a gland that secretes mucus opens. In addition to this gland, numerous mucous glands are scattered over the entire surface of the body, so the entire body of slugs is covered with mucus. The main purpose of mucus is to moisturize the skin. There is a genital opening on the right side of the neck. The mantle has the appearance of a flat thickening on the dorsal side of the body. Near the right edge of the mantle there is a breathing hole leading to the lung cavity. An anus and an excretory pore open near the respiratory opening along the right edge of the mantle. Slugs are bisexual animals. During mating, male gametes are exchanged. Eggs are laid in moist shaded places.

Most slugs feed on plants, lichens, or fungi. Predatory slugs feed on oligochaetes or other types of molluscs. Active at night, hiding during the day. Slugs that settle in areas occupied by agricultural crops can cause significant damage to plantings of cultivated plants. For example, the field slug (Agrolimax agrestis) eats sown grains and shoots of winter wheat and rye, while the net slug (Deroceras reticulatum) causes great damage to the crop of tomatoes and cabbage.

Description of classes, subclasses and units of the Mollusk type:

• Class Gastropoda (Gastropoda)

  • Subclass Pulmonary (Pulmonata)

The common pond snail is the most common member of the family in Europe. It feeds on waste and carrion that other animals do not consume.

   Class - gastropods
   Row - Basommatophara
   Genus/Species - Lymnaea stagnalis

   Basic data:
DIMENSIONS
Shell length: 45-70 mm.
Shell Width: 20-30 mm.

BREEDING
Mating period: spring or summer when the water warms up.
breeding type: pond snails are hermaphrodites.
Number of eggs: 200-300 eggs in cords attached to underwater objects. Eggs hatch into miniature replicas of adults.

LIFESTYLE
Habits: kept alone in stagnant ponds and rivers with a slow current.
Food: organic waste and algae, sometimes carrion.
Lifespan: 3-4 years.

RELATED SPECIES
About 100 species belong to the family of pond snails, for example, eared, marsh and small pond snails.

   An ordinary pond snail lives in water, but breathes atmospheric air. That is why it can inhabit reservoirs with stagnant water, which contains a minimal amount of oxygen. In such swamps and lakes there are many rotten plant and animal remains - the main food of an ordinary pond snail.

BREEDING

   Ponds are hermaphrodites. Each individual has both male and female reproductive organs. Despite this, during mating, both partners mutually fertilize each other. Later, the pond snails lay their eggs in long dragline cords. Cords are attached to the underwater parts of plants and rocks. Sometimes they even stick to the shells of other individuals. Pond snails do not have a free-swimming larva stage. Each egg develops an embryo, which, after leaving the shell, looks like a smaller copy of an adult.

LIFESTYLE

   Many snails that live underwater breathe with filiform gills. The gills of these cephalopods contain many blood vessels. Animals get oxygen directly from the water. However, in a common pond snail, the respiratory organs are in the form of lung sacs. The mantle cavity of these cephalopods, which is connected to the external environment only through a small respiratory opening through a pneumostome, penetrated by a dense network of small blood vessels. It acts like a human lung. The disadvantage of this type of breathing is the need to emerge about every 15 minutes in order to replenish air supplies. However, thanks to this respiratory organ, the pond snail can live in water bodies with a low oxygen content.
   The pond can move freely from the underside of the surface water film. This is possible due to the fact that with the help of the lungs, the mollusk scoops up a large amount of air, which raises it to the very surface.

FOOD

   In stagnant water, on submerged tree trunks or stems of aquatic plants, organic matter and microorganisms settle, which contribute to their decomposition. Pond snails eat this layer of organic debris, waste, bacteria, protozoa, blue-green algae, and mud. These molluscs are omnivores. The snail also feeds on the eggs and larvae of other aquatic animals and also attacks injured fish, tadpoles or newts.
   With the help of the radula, the pond snails eat water leaves and scrape algae from the lower surface of the water lily leaves. The radula of the gastropods resembles a sharp file, which is constantly updated, as it wears out rather quickly. The anterior worn teeth on the radula are periodically replaced by new sharp teeth. The basis of the radula is chitin, a chemical compound found in the strong shells of insects. The radula of the pond snail acts like a grater. Carnivorous snails, using the radula, punch a hole in the shell of other mollusks and get inside. Under unfavorable conditions, the growth of pond snails stops.

OBSERVING THE POND

   Common pond snails are found in ponds, lakes or rivers. They can only live in hard water. From hard water, pond snails get lime, which they need to build a "house" and shells. In areas where the main rock is limestone or similar sedimentary rocks, pond snails can live almost anywhere: in small lakes, ponds, ditches filled with water, in irrigation canals and rivers. Ordinary pond snails can be housed in aquariums, where they slowly travel across the glass and scrape off a layer of algae from it with a radula. These gastropods can swim near the very surface from the underside of the water film. A disturbed pond snail "falls" to the bottom.
  

DO YOU KNOW WHAT...

• 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.
• The small pond snail is one of the smallest representatives of the family. It lives not only in reservoirs, but also in water meadows and pastures. The small pond snail is an intermediate host of the liver fluke, which causes fascioliasis in sheep and cattle.
• The shells of all European species of pond snails are twisted to the right. Only as an exception are individuals with left-handed (leotropic) shells.

  

FEATURES OF THE ORDINARY POND

   Horn Coil: a close relative of the pond snail lives in the same area. However, it is much smaller than the pond snail, in addition, it has a shell of a different shape. Sometimes you can see a horn-like coil that is attached to the shell of an ordinary pond snail.
   Tentacles: grow on the sides of the head, they are flattened and triangular, which distinguishes them markedly from the filamentous tentacles of other snail species. The tentacles perform only the function of the organ of touch. The eyes are located at their base.
   Sink: ends with a long tip. Consists of lime and covered with a yellowish stratum corneum. It is quite thin and easily damaged.
   Eggs: the pond snail lays in long dragline cords that are glued to various underwater objects. The number of eggs in a clutch varies between 200-300 pieces. The eggs are surrounded by a slimy mass, which is dressed like a special capsule, or cocoon. Hatched from eggs, outwardly resembling miniature copies of their parents.

PLACES OF ACCOMMODATION
The pond snail lives in ponds with stagnant water and in rivers with a slow current. It is found in Central, Western and Southern Europe, in South-West Africa and Asia Minor, and from there the range of the pond snail reaches South-West India.
PRESERVATION
Prudovik is not threatened with extinction, but they are currently being polluted by the natural environment.