Who eats snails in a pond. Type of shellfish. Class Gastropods. Big pond snail. The most common types
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Pond snails are freshwater lung mollusks distributed throughout the world. This family includes a huge number of species, but among them the most famous is the common pond snail, which has the largest size.
Large individuals reach 7 centimeters in length. These snails live in ponds, small lakes and river creeks from spring to autumn.
Large mollusks crawl quite interestingly along the bottom of the reservoir and aquatic plants. The largest number of pond snails is found in mid-summer among water lilies.
These mollusks are omnivores. Crawling over aquatic plants, they scrape off algae from them with the help of their radula, and at the same time eat the smallest living creatures that come across on the way. Pond fish are very voracious; they eat not only plant and animal food, but also carrion.
Pond snails often rise to the surface of the water, suspend themselves from the water film from below using a wide sole, and swim slowly in this position. Pond snails rise to the surface of the water for a reason. Although they live in water, they breathe, like all pulmonate mollusks, using their lungs, which is why they must rise and take air into their lungs. When a mollusk takes a breath of air, its respiratory opening, which leads into the pulmonary cavity, is wide open. The presence of lungs indicates that the ancestors of pond snails are land mollusks, and they returned to the water a second time. Pond snails are freshwater mollusks.
Reproduction of pond snails
During the mating process, pond snails mutually fertilize each other, since they are bisexual creatures. Pond snail eggs are long, transparent, gelatinous cords that are attached to a variety of underwater objects. The eggs can even attach to another pond snail.
Thanks to this structure, the egg is provided with nutrients and protected from environmental influences. Inside the eggs, pond snails develop without the free-swimming larval stage. Most likely, this structure of eggs in pond snails is due to their connection with land ancestors, where such adaptations were more important than in water. The size of the clutch and the number of eggs in it can vary significantly. Sometimes there are up to 270 eggs in one cocoon.
Pond snails differ markedly from each other, and their size, color, thickness and shape of the shell can vary significantly. Available as large individuals, and practically dwarf ones, which have not matured due to poor nutrition or unfavorable external factors. In some individuals the shell consists of thick walls, while in others the shell is very thin and fragile, it breaks at the slightest impact. The curls and shape of the mouth vary greatly. The color of the body and legs can vary from sandy yellow to blue-black.
Thanks to this tendency for pond snails to vary, a huge number of varieties of mollusks have formed within the species. Therefore, it can be difficult for even scientists to determine whether a particular individual is simply a variety or a new subspecies.
Species of pond snails
In our reservoirs, not only common pond snails are often found, but also another species - the long-eared pond snail. In addition, the marsh pond snail and the egg-shaped pond snail live in stagnant water.
By 6-7 months, small pond snails reach sexual maturity, and they live for about 2 years. An egg cocoon can contain from 4 to 25 eggs. Young individuals develop over 10-20 days.
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 You can observe these snails 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 prudovik is one of the most voracious inhabitants fresh water. 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 had higher value 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 major 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 arose big number local varieties that differ 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 quantities. However, in mid-summer the snails disappear as their life cycle ends in one season.
The small pond snail is one of the most common species of snails in the reservoirs of our country. It has an elongated, pointed shell and a short, wide leg. It reproduces easily and quickly and is a hermaphrodite.
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