Eared pond snail. The small pond snail is a snail from the reservoirs of our country! 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

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 most large sizes.

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 most large number pond snails are 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 clam 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.

Caviar has a complex structure - the egg cell is immersed in a mass of protein, and on top it is protected by a double shell. In turn, the eggs are in a mucous mass and are dressed in a special shell or cocoon. A cord extends from the inner part of the shell, the second end of which is attached to the outer shell of the egg, that is, it turns out that it is suspended from the wall of the cocoon. This complex structure of eggs is characteristic of many species of mollusks.

Thanks to this structure, the egg is provided with nutrients and protected from exposure external environment. 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. There are both large individuals and almost dwarf ones that 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.

Family representative freshwater mollusks group of gray-eyed people. It has an elongated shell, strongly pointed towards the apex, curled to the right, usually thin and translucent. The shell curls expand very quickly and the last one, the so-called belly, occupies the most significant part of the shell. Its color is pale yellowish.
The pond snail, like the reel, is one of the mollusks with pulmonary respiration and therefore from time to time floats to the surface to inhale atmospheric air. Its body is greenish-dark gray in color with yellow spots. The head is equipped with two triangular flat tentacles, at the base on the outer side of which there are eyes. The leg is shorter than the reel leg, but significantly wider. From the leg, the body inside the shell rises upward in a spiral and forms, closer to the opening of the shell, a kind of sac that contains a mass of vessels and serves as a respiratory organ. On its right side there is an opening for air intake, which is closed by tightly locking muscles. The hole and the entire respiratory organ are easily visible when the animal, crawling along the plant, turns and often almost completely crawls out of the shell. This often happens when the pond snail, like a reel, crawls with its foot along the surface of the water, which it does in order to breathe atmospheric air.
Under the head there is a mouth opening, consisting of an upper jaw and two lateral sickle-shaped ones. A long tongue is also placed here, which scoops up algae. This is especially clearly visible when a pond snail crawls along the glass of an aquarium.
Pond snails are bisexual animals, and therefore they can be found mating 6-10 pieces together. Pond snails lay their eggs on the lower surface of floating leaves, on glass in an aquarium, and on various objects. The caviar is not connected in a flat cake shape, but in a worm-shaped or oval shape, similar to an icicle. From May to August they lay up to 20 such icicles, and each icicle contains 20-100 eggs. The eggs are transparent. The development of the embryo proceeds quickly, and after just a few days the embryo, covered with ciliated hairs, begins to rotate rapidly.
The snails hatch from their eggs no earlier than twenty, and sometimes even forty days, which, in all likelihood, depends on both the water temperature and the intensity of the lighting.
A remarkable phenomenon is sometimes observed with the gelatinous mass of eggs of these snails. It is covered with some kind of mold - small cilia with a pin-shaped thickening at the end, apparently, lily of the valley. These creatures apparently contribute to the destruction of this mass.
Snail reaches large sizes, and therefore not very convenient for an aquarium. This inconvenience is increased by the fact that it grows so quickly and beyond short time reaches large sizes.
Along with its rapid growth, this snail is distinguished by its gluttony, which preys on aquarium plants, with particular preference for plants that are at the same time soft and juicy. When young, the pond snail is not dangerous, since it is small and its appetite is insignificant.
Pond fish are capable of eating the corpses of their own brothers.
The same genus of pond snails also includes Limnea stagnalis (common pond snail), even larger than the above.

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 lung is calm state the mollusk prevents it from falling to the bottom. But if you touch an ordinary pond snail at this time, it instantly releases the air from 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, from dark blue to yellow flowers. The shell has a thin translucent structure.

Food and habitat

Common pond snails They are omnivorous animals, they can eat both plant and animal foods, mainly algae, aquatic plants, uruti leaves, etc. Common pond snails are widely distributed throughout to the globe, mainly on ponds, rivers, lakes, etc. They live at shallow depths.

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

Structure

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

Nervous system is a peripharyngeal nerve ring formed by nerve ganglia, from which nerves extend to all organs. The tentacles are equipped with tactile receptors and chemical sense organs (taste and smell). There are also balance organs.

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

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

Pond snails are pulmonary mollusks. They are distributed throughout the world and live in fresh water bodies. People often have many questions about the structure and life functions of these representatives of the animal world.

General characteristics

Lakes and rivers are home to representatives of the class of gastropods, one of the most numerous and diverse groups in the world. The large pond snail reaches five centimeters and has a cone-shaped shell twisted into a spiral. Sink not only serves as a home for the mollusk, it protects its soft parts. The shell is tightly connected to the muscles of the pond snail and consists of green lime. In the body of a pond snail, its main body parts, such as the head, torso and leg, are clearly visible.

Transitions from one part to another are completely devoid of sharp boundaries. The leg is the strongest part of the body of a mollusk. When a mollusk needs to move, it initiates wave-like muscle contractions along the leg, thereby being able to move unhindered along the bottom of the reservoir. The leg is located on the ventral side of the body. A large pond snail, whose shell completely follows the shape of the body, has a large head. There is a mouth on the lower part of the pond snail's head, and tentacles are visible on the side, which help the mollusk sense space. The animal also has eyes.

Digestive system of the pond snail

The large mollusk feeds on aquatic plants and small insects. It should be noted that big pond snail very gluttonous. Using its tongue, it gently scrapes off the top layer of the plant. Small cloves that look more like a grater help him in this. After the plant particles enter the pharynx and then the esophagus, they are sent to the mollusk’s stomach, where they are processed and go into the animal’s intestine. After some time, processed food is excreted through the anus.

Respiratory system of a pond snail

This type of mollusk has a round breathing hole, with the help of which the pond snail fills its lungs with clean air. Often these animals rise to the surface of the water and swim slowly. You can see exactly how the mollusk breathes, because when it inhales, its respiratory opening is as open as possible. The presence of lungs confirms the fact that the ancestors of pond snails were land mollusks. The walls of the lung of a mollusk are tightly intertwined with vessels; in this place, the blood fills with oxygen and releases carbon dioxide.

The mollusk must often rise to the surface of the water to breathe, otherwise the animal may simply die. On average, a pond snail rises to the surface of the water 7 times per hour. Oddly enough, the mollusk has a two-chambered heart that beats up to 30 times per minute. The heart disperses the pond snail's blood through the vessels. It should be noted that the mollusk has colorless blood. The nervous system is located in the pharynx area; it consists of special nerve nodes that give impulses throughout the mollusk’s body.

Pond snail behavior

The prudovik leads an active lifestyle. He constantly crawls among the thickets and scrapes top part plants. The speed of the mollusk reaches 25 centimeters per minute. It never stops at one area of ​​water, but constantly moves around. Even after catching a pond snail while relaxing in nature, a person may notice the excessive activity of this animal.

Often aquarium lovers want to take a pond snail to their home and place it with other fish. But we must remember that a pond snail caught in natural environment and transferred to an aquarium with other fish, can be dangerous. The fact is that we cannot rule out infections that the pond snail can infect the inhabitants of the aquarium; this can become a real tragedy for the owner. The first thing you need to pay attention to is the signs of a large pond snail and its behavior.

Reproduction of pond snails

The large pond snail is a bisexual creature, therefore, during mating, individuals engage in mutual fertilization. The genitals look like oblong cords and are attached to any underwater objects. The egg cell is covered with a double protective shell and is dressed in a cocoon.

The pond fish can lay a clutch of about 300 eggs. But the number of eggs may vary. The most surprising thing is that, like the snail, the large pond snail does not have a developmental stage with a larva. The eggs hatch into a small pond snail with a thin shell. It is worth noting that not all pond snails become large individuals upon completion of adulthood. It all depends on nutrition and external factors.

Not only large pond snails live in reservoirs, but also small ones. The small pond snail is a small snail that can be found in all water bodies of the country. They can be found in springs and puddles, posing a huge danger to humans. Such pond snails are carriers of flukes, and most often they are exterminated.

One more interesting view The mollusk is toothless. The large pond snail is very different from this species, but they can easily live in the same place. Toothless has a bivalve shell, which also consists of lime. Circulatory system The mollusk is very similar to the pond snail.

Representative of the genus is also close to pond snails Mikas . It has a very fragile shell. They live in lakes and ponds. They reproduce at an incredible rate, but live only one season.

Among mollusks there are species that do not have shells at all, such as slugs.
All shellfish are an integral part of the food chain. So, mollusks eat small insects, but they themselves become food for fish.