In this article we will look at who the 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 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 snail
The large pond snail belongs to the class of gastropods, which is the most numerous and diverse compared to 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 its brothers.
Let's talk about the external structure of a large pond snail. It consists of three parts that are noticeable and clearly distinguishable from each other. The body outside the shell is covered with a mantle to protect the internal mucous membrane; the shell of the mollusk is twisted for convenience into a spiral of 5 turns. This structure of the shell provides reliable protection of the body from irritants and mechanical damage. . The sink contains lime for the basis of the structure of the spirals, and on top it is covered with an organic substance of a horn-like type (this is found on the horns of cattle, etc.).
Due to the structure of the shell, it received an asymmetrical body to better fit into the “protection”; the shell is connected to the body by a muscle. The muscle allows the animal to be pulled inside the shell, and with the help of a pronounced leg, the mollusk can crawl back out.
In the internal structure For pond snails of any type, everything is arranged simply. The main organs are:
- digestive complex;
- leg;
- eyes;
- excretory and respiratory system;
- sole and mucus secretion glands.
The snail feeds on plant food in crushed form, then the food from the tongue (has a “grater”) passes into the pharynx, is processed by the secretion of splitting and processed in the stomach and intestines.
The circulatory system is not closed, and the mollusks move due to their powerful legs, which glide over any surface thanks to the secretion secreted by the glands.
These animals are unique and there is no need to kill them. . They don't harm anyone, nor gardens, because they feed on plant foods that are easily processed (that is, weeds such as ephemerals (wheatgrass, woodlice). Snails also have healing properties; when properly fed and used, they secrete mucus that nourishes human skin and regenerates epithelial cells .
Small pond snail
Who are pond snails? in general, you know from the previous paragraphs, now we will talk about small things. There are several small pond snails in nature:
Small snails are found in all gardens, are small in size and beautiful in appearance. Be kind to snails, they do no harm, more good.
Common pond snail
The common pond snail is found in central Russia and Europe. The pond snail is large in 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, and they feed on tough 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. The color of the shell is pearlescent brown. Body color – brown, gray, white.
Snails can easily survive both in nature and in the artificially created environment of a terrarium or aquarium. The snail moves thanks to the secretion of mucus and the outer sole, which allows it to move quite quickly over various distances. Snail mucus is rarely used in cosmetology, but most often the mollusk is used for decoration.
Mollusks become attached to people - breeders, so if you fall in love with a snail, do not give it to others, otherwise the animal’s weak heart will not stand it.
Now let's take a look at the photo of the pond snail
Great pond snails
Common pondweed– lat. Limnaea stagnalis, a member of the phylum Mollusca, belongs to the class Gastropods. A feature of the common pond snail, like all representatives of the pond snail family, is its peculiar swimming in water. A special organ (leg) is directed upward during movement, protruding slightly on the surface of the water. To prevent the common pond snail from drowning while moving, the middle of the leg bends down, thus acquiring the shape of a boat, while the animal’s shell is directed down to the bottom. Scientists do not yet understand this peculiar movement.
Structure
The snail's eyes are located at the base of the second pair of tentacles. The common pond snail breathes through one lung, which is a modified mantle cavity. The air in the lungs, in a calm state of the mollusk, prevents it from falling to the bottom. But if at this time you touch an ordinary pond snail, it instantly releases air from the respiratory tract and instantly falls down. It also has one kidney and one atrium. The shell of the common pond snail has the shape of a twisted spiral.
Animal characteristics:
Dimensions: clam length 5 – 7 cm.
Color: The common pond snail has variable colors, ranging from dark blue to yellow. The shell has a thin translucent structure.
Food and habitat
Common pond snails are omnivores; they can feed on both plant and animal foods, mainly algae, aquatic plants, uruti leaves, etc. Common pond snails are widely distributed throughout the globe, mainly in ponds, rivers, lakes, etc. They live at shallow depths.
Pond snails are gastropods.
The largest of the domestic representatives of the pond snail family (Limnaeidae) - common pond snail (Limnaea stagnalis), having an elongated conical shell up to 55 mm high. U eared pond snail (L. auricularia) shell with a short curl, resembling an ear (height 26 mm). Marsh pond snail (L. palustris) similar to the common one, but its shell has the shape of a sharp cone with a small hole (shell height 32 mm). Sink egg-shaped pond snail (L. ovata) with a short whorl, and its last whorl with a wide ovoid opening (shell height 18 mm).
Pond fish live in freshwater bodies of water. The common pond snail is especially widespread. It stays near the surface of the water and is easy to catch. In the jar, it slowly crawls along the walls of the vessel. SlipperThis occurs due to the fact that the muscles of the sole of the wide leg contract in a wave-like manner.
Ponds: 1— ordinary; 2 - ear; 3 - swamp; 4 - ovoid
Pond snail structure: 1— oral lobes; 2— tentacles; 3— eyes; 4 - leg; 5— breathing hole
Pond snails can wander along the underside of the surface film of water, holding onto it with the help of their soles. At the same time, a ribbon of mucus remains behind them. It is believed that this movement is due to the surface tension of water.
The pond snail has air inside its respiratory cavity, which, like the swim bladder of a fish, supports it. If you give a slight push to a crawling snail, it will submerge in the water and float up again, like a cork. The cochlea can arbitrarily compress the respiratory cavity and, due to a decrease in specific gravity, sink to the bottom; when the cavity expands, it floats to the surface.
Pond fish are capable of staying under water for a very long time. This is explained by the fact that the closed lungIn this cavity, air is used very rationally during breathing, and oxygen is gradually replaced by carbon dioxide. In addition, it is likely that respiration also occurs through the skin, using oxygen dissolved in water.
Pond snails feed on the leaves and stems of aquatic plants. Therefore, individuals of large species cannot be planted in a decorative aquarium. In addition to plants, they eat small organisms (hydra, protozoa), fish eggs, meat and even the remains of dead fish and snails. So it is better to keep pond snails in a separate container.
When breeding, these snails lay eggs on aquatic plants and other objects. The masonry has the appearance of a transparent gelatinous sausage. In twenty daysThe eggs hatch into tiny snails, which, feeding on plant foods, grow quite quickly. This whole process can be observed in the aquarium.
All pond snails, like most gastropods, are hermaphrodites.
More interesting articles
The large pond snail is a typical representative of freshwater. In our article we will look at the living conditions and typical structural features of this animal.
Mollusks: features of organization
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. They can be found in fresh and salt water bodies. Thus, toothless and pearl barley live in ponds and lakes, and mussels and octopuses live in the seas. Snails and slugs can be found in damp areas of land.
The body of mollusks can be divided into three parts: head, torso 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 called the mantle.
Basics of classification
Depending on the structural features, three classes of mollusks are distinguished. A characteristic feature of cephalopods is the modification of the legs into tentacles. They are located around the mouth. There are suction cups on the tentacles, with the help of which animals catch and hold prey. Cephalopods are capable of jet movement thanks to a special tubular formation - a funnel. Representatives of this class are squids, cuttlefish and octopuses.
These include pearl barley, zebra 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 gastropods. Let's look at its structure in more detail.
Large pond snail - a representative of gastropods
Large, or found in fresh water bodies rich in vegetation. Its body, like that of all gastropods, consists of a head, torso and legs. The middle part is located entirely inside a spirally twisted shell, consisting of lime, covered with a layer of horn-like substance. This is a kind of home and shelter. The shell of a large pond snail is spirally twisted. The maximum is 4-5 revolutions. It has an opening called the orifice. The head and leg are pulled in through it. The shell of a large pond snail and a horny coil is closed with a special lid in case of danger. This structure provides additional protection against enemies.
The structure of a large pond snail
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 ventral part of the body. Its surface secretes mucus, which allows it to glide easily over various substrates and water films.
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. Pond fish also have balance organs. They are represented by small bubbles, inside of which special bodies are located. Changing the position of these structures maintains the mollusk's balance.
Circulatory and respiratory systems
A large pond snail has a type. It consists of a two-chambered heart and a vascular system. Blood mixes with the cavity 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 the 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 the 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 large pond snail moves slowly but surely. Why does he constantly “travel”? The mollusk moves in search of food, scraping it from underwater objects using its jaw and grater. The latter consists of several rows of horny denticles. The process of breakdown of nutrients is accelerated by enzymes of the digestive glands - salivary and liver.
The anus opens above the pond snail's head. And next to it, the duct of the urinary system opens. The latter is represented by a single kidney and a ureter with an opening.
Reproduction and development
According to the type of reproductive system, the large pond snail is a hermaphrodite. This means that both female and male reproductive cells are formed in his body. Fertilization in these mollusks 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: the large pond snail is a representative of gastropods. These are typical inhabitants of fresh water bodies. Pond snails have three body parts: head, torso and leg, as well as a spirally twisted shell.
The pond snail family includes well-known freshwater lung mollusks that are widespread throughout the world.
Of the large number of species belonging to this family, the most famous for its large size is the common pond snail, the largest specimens of which reach 7 centimeters. From early spring to late autumn, these snails can be observed in ponds, river backwaters, and small lakes. It is interesting to watch how these bulky snails crawl along aquatic plants or along the bottom of a reservoir. There are especially many of them in mid-summer among the floating leaves of egg capsules or water lilies.
Pond snails are omnivores, therefore, crawling along the leaves and stems of aquatic plants, they scrape off algae from them with their radula, and at the same time consume small animals that come across their path. The pond fish 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 suspended from below with the wide sole of its foot, slowly and smoothly glides in this position due to the surface tension of the water film. It is not in vain that pond snails rise to the surface of the water. Although they are aquatic organisms, like all pulmonate mollusks, they breathe using the lung and are forced to rise to the surface to “sip” air. The respiratory opening of the pond snail, leading to the pulmonary cavity, is wide open. The presence of lungs in pond snails indicates that these animals originated from land mollusks and have returned to living in water for the second time.
Reproduction of pond snails
When mating, pond snails mutually fertilize each other, since, like all pulmonate 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 the eggs even stick to the shell of another individual of the same species. Pond snail eggs are a complex formation, since the egg cell is immersed in a mass of protein and covered on top with a double shell. The eggs, in turn, are immersed in a mucous mass, which is covered with a special capsule, or cocoon. A cord 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 if suspended from the wall of the cocoon. The complex structure of the egg clutch is also characteristic of other freshwater pulmonate mollusks. Thanks to these devices, the egg is provided with nutritious material and protected by strong shells. Inside these shells, pond snails develop without the stage of free-swimming larvae. It is likely that such protective devices of pond snail eggs were inherited from their land ancestors, where these devices were of greater importance than when living in water.
The number of eggs in a clutch varies quite widely, as does the size of the entire clutch - the mucus cord. Sometimes you can count up to 270 eggs in one cocoon.
Pond snails are characterized by extreme variability, 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 insufficient nutrition. Some pond snails have a shell with 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 mollusk varies from blue-black to sandy yellow.
This “propensity” for variability played a big role in the evolution of pond snails. Within species, a large number of local varieties have arisen, differing in the listed characteristics, and it is often very difficult to determine whether this is a geographical subspecies or a variation due to specific living conditions in a given body of water.
Species of pond snails
Along with the common pond snail, a permanent inhabitant of our inland waters, there is another, also extremely variable species - the long-eared pond snail. In addition, the ovoid pond snail, marsh pond snail and some others live in stagnant reservoirs.
Interestingly, pond snails living at considerable depths have been found in deep-sea lakes in Switzerland. At the same time, they are no longer able to rise to the surface to breathe air and have developed another adaptation. The pulmonary cavity of these snails is filled with water, and they breathe oxygen dissolved in water. The absence of gills in pond snails, in contrast to primarily aquatic mollusks, again proves their origin from land snails.
The only representative of our fauna from the genus Myxas is close to pond snails, differing from them in a very thin and fragile shell, almost completely covered with a mantle. Thus, the shell of this mollusk turned from external to internal. These snails live mainly in floodplain ponds and lakes, where they sometimes breed in huge numbers. However, in mid-summer the snails disappear as their life cycle ends in one season.
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