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

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 big 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 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.

Caviar has 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 conditions. 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 habitat of Lymnaea stagnalis is very extensive - bodies of water North Africa And North America, Asia, Europe.

The Common Prudovik snail is able to live both in fast streams and in swamps, but it feels best in the coastal part of lakes. The pond snail actively crawls along the bottom of the reservoir and coastal vegetation, and sometimes comes out onto wet meadows.

The main difference between this one is that its eyes are located at the base of the antennae.

The Prudovik shell has Brown color, which sometimes goes dark. The base of the shell is quite fragile, the number of curls varies between 4-5, the dimensions of the shell are up to 55mm in height and up to 30mm in width. Lymnaea stagnalis are able to move vertically (by secreting a path of mucus, they crawl along it in all directions).

Snails breathe atmospheric air using the lung (a special part of the mantle cavity). To renew the air in the pulmonary cavity, the mollusks rise to the surface of the water and breathe using the edge of the mantle rolled into a tube.

In water rich in oxygen, pond snails are able to live at depth without rising to the surface. In this case, the lung is filled with water, through which gas exchange occurs.

The Prudovik snail feeds on both plant foods and small insects and microorganisms. Quite often you can see snails eating the foliage of aquatic and coastal plants. If the number of mollusks in a reservoir increases greatly, this is very harmful to the surrounding plants.

In the aquarium, the Common Prudovik can be fed with cabbage stalks, lettuce or raw potatoes.

Many freshwater inhabitants don’t mind eating this snail, as well as its caviar.

Reproduction

By nature, Lymnaea stagnalis are hermaphrodites, so the eggs are fertilized both by their reproductive products and by other snails.

at one time the snail lays a large number of eggs, enclosed in transparent mucous clutches.

In an aquarium, breeding of the pond snail is difficult, since most of the eggs laid are eaten.

The Prudovik snail reaches sexual maturity when its shell grows to 20 mm in length.

The small pond snail is similar to the common pond snail, only the size of the shell is smaller (see appendix, Fig. 25). The small pond snail lives in temporary reservoirs - puddles, ditches, swampy meadows, sometimes even on wet soil near the water's edge. In a word, there are many places where temporary residents can be found.

Like its relative, it feeds on algae and microorganisms.

The small pond snail is widespread throughout Europe and North Asia, like the common pond snail.

Gastropods;

coil family;

horn coil.

Coils (Planorbis) belong to the class Gastropoda, to the order Pulmonata, to the family of coils (Planorbidae).

The reel can be distinguished at first glance due to its extremely characteristic
shell, curled in one plane in the form of a spiral cord.
The most eye-catching is the horny coil (P. corneus L.), the largest among the others (shell diameter 30 mm, height 12 mm), reddish-brown in color. This reel is found everywhere in both pond and lake waters.
The movements of the coils resemble the movements of pond snails. When crawling, snails expose their dark, soft body far from the shell and move along underwater objects with the help of their wide, flat legs. The head has a pair of thin tentacles, at the base of which are eyes. Coils, just like pond snails, can wander along the surface of reservoirs, suspended from a film of surface tension of the liquid.
The coils breathe atmospheric air, drawing it into the pulmonary cavity formed by the walls of the mantle. The breathing hole leading into the indicated cavity opens on the side of the body, near the edge of the shell. It opens when the coil rises to the surface of the water for a supply of air. When there is a lack of air, the coil uses a special leathery outgrowth, which is placed on the body near the pulmonary opening and plays the role of a primitive gill. In addition, the coil, in all likelihood, breathes directly through the skin.
Nutrition. Coils feed on plant matter by eating plant parts that are scraped off using a grater. These snails are especially willing to eat the green coating of small algae that forms on the walls of the aquarium. From the outside, through the glass, it is not difficult to observe how the animal uses its grater, raking up plaque like a spatula. It is very possible that the coils can also feed on animal food. At least in captivity, they willingly pounce on raw meat.
Reproduction. Coils reproduce using eggs that are laid on the leaves of aquatic plants and other underwater objects. The clutch of the horny coil is constantly encountered on excursions and is so characteristic that it can be distinguished without difficulty: it looks like a flat gelatinous oval plate of yellowish or light brown color and contains several dozen round pinkish transparent eggs. After two weeks or more (depending on the water temperature), the eggs hatch into tiny snails that grow quite quickly. The eggs of spools, like other snails, are readily eaten by fish and destroyed by them in large quantities. Like the pond snail, spoolies are hermaphrodites.
The behavior of the coils when the reservoirs in which they are found dry out is interesting. They burrow into moist mud, like the large horn spool (P. corneus). Sometimes this coil remains on the surface of the soil, sticking its mouth to the silt if there are residual moisture in it, or it releases a dense film insoluble in water, which closes the hole of the shell. In the latter case, the body of the mollusk gradually contracts, eventually occupying a third of the shell, and the weight of the soft parts drops by 40-50%. In this state, the mollusk can survive out of water for up to three months (marginal coil P. marginatus P. planorbis).

The body of the coil, like that of pond snails, is divided into three parts: head, body and leg (see Appendix, Fig. 26). The leg is the muscular abdominal part of the body, on which the mollusk slowly glides. In coils, the shell turns are located in the same plane. The coils are not as mobile as pond snails and cannot be suspended from the surface film.

Coils live on plants in stagnant and slow-flowing reservoirs, in the same place as the common pond snail, but they rise to the surface of the water much less often.

beauty's family;

larva of a beauty girl.

On a sunny day, blue lights flash and then go out over the river (see appendix, Fig. 27). Graceful dragonflies flutter about. At some point they resemble helicopters.

The body is bronze-green, the wings of females are light smoky, and those of males are almost entirely blue.

All dragonflies, wherever they are, wherever they fly, need water. They lay eggs in the water. And only in water can their larvae live. The larvae do not look like adult dragonflies. Only their eyes are the same.

Special mention must be made about the eyes of dragonflies. Each eye consists of thousands of small ocelli. Both eyes are large and protruding. Thanks to this, dragonflies can look in all directions at the same time. This is very convenient when hunting. After all, dragonflies are predators. And their larvae that live in water, too.

Dragonflies hunt in the air - they grab insects in flight. The larvae live in water and get their food here. But they do not chase prey, but lie in wait for it. The larva sits motionless or crawls slowly along the bottom. And tadpoles or some insects swim by. The larva doesn’t seem to care about them, but how will this tadpole or insect turn out to be close. Once! She throws it away instantly long arm and grabs the prey, quickly pulling it towards itself.

“But insects don’t have hands,” you say. And you'll be right. Yes, of course, they don't have hands. But there is a very long lower lip with hooks at the end. The lip folds like a hand at the elbow when you press the hand to the shoulder. And while the larva watches for prey, the lip is not visible. And when the prey is close, the larva instantly throws out its lip to its full length - as if shooting it - and grabs a tadpole or insect.

But there are moments when the larva needs to be saved. And here her speed saves her. More precisely, the ability to move from place to place with lightning speed.

Some predator rushed at the larva. Another second and the larva disappeared. But where is she? I was just here, and now I’m in a completely different place. How did she end up there? Very simple. Activated her " jet engine".

It turns out that dragonfly larvae have a very interesting adaptation: a large muscular sac inside the body. The larva sucks water into it and then throws it out with force. It turns out to be a water “shot”. The water jet flies in one direction, and the larva itself flies in the opposite direction. Just like a rocket. This is how it turns out that the larva makes a lightning-fast dash and slips away from under the very “nose” of the enemy.

After flying a few meters, the larva slows down, sinks to the bottom or clings to some plant. And again he sits almost motionless, waiting for the moment when he can throw out his “hand” and grab the prey. And if you need it, it will relaunch its " rocket launcher". True, not everyone has a “jet engine”, but only the larvae of large dragonflies.

After a year, the larvae of some dragonflies, and after three years, the larvae of others climb out to the surface along some plant sticking out of the water. And then it happens small miracle: The skin of the larva bursts and a dragonfly emerges from it. The most real and not at all like a larva.

The dragonfly will shed its skin like a suit, and even pull out its legs as if from stockings. He will sit for a few hours, rest, spread his wings and take off on his first flight.

Some dragonflies fly far from their birthplace. But the time will come, and they will definitely return. Because they cannot live without a river or lake, pond or swamp - without water, in a word. And the river, pond, lake also cannot live without these friends.

Dragonfly eggs are laid in water or in the tissue of aquatic plants. Larvae hatch from eggs extremely characteristic shape, interesting in their own way biological features. These larvae play an important role among other living material of freshwater excursions.
Dragonfly larvae are found everywhere in standing and slowly flowing water. Most often they are found on aquatic plants or on the bottom, where they sit motionless, sometimes moving slowly. There are species that burrow into silt.

The larvae move either by swimming or crawling. Larvae from the lute group swim differently than others. An important role in movement is played by the expanded gill plates located at the rear end of the abdomen, which serve as an excellent fin. Bending long body, the larva hits the water with this fin and rapidly pushes forward, moving like a small fish.

Dragonfly larvae feed exclusively on live prey, which they stand motionless for hours on end, sitting on aquatic plants or on the bottom. Their main food is daphnia, which they eat in huge quantities, especially by younger larvae. In addition to daphnia, dragonfly larvae readily eat water donkeys. They consume cyclops less readily, perhaps due to the latter’s small size.
The favorite food of dragonfly larvae is also mayfly larvae and mosquito larvae from the families of culicids and chironomids.
They also eat larvae water beetles, if only he is able to master them. However, they do not touch large larvae of swimming beetles, well armed and no less predatory, even if they are placed in a common vessel with them.
Dragonfly larvae do not chase their prey, but sit motionless on aquatic plants or on the bottom and guard their prey. When a daphnia or other animal suitable for food approaches, the larva, without moving from its place, quickly throws out its mask and grabs its victim.

For grasping prey, the larvae have a remarkable oral apparatus, aptly named “masks.” This is nothing more than a modified lower lip, which looks like grasping forceps sitting on a long lever - a handle. The lever is equipped with a hinge joint, thanks to which this entire device can be folded and, when at rest, covers the underside of the head like a mask (hence the name). Having noticed the prey with its large bulging eyes, the larva, without moving from its place, targets it and, with a lightning-fast movement, throws its mask far forward, grabbing the victim with remarkable speed and accuracy. The caught prey is immediately devoured using strong gnawing jaws, while the mask brings the victim to its mouth and holds it like a hand while eating.

Breath. Dragonfly larvae breathe through tracheal gills. In lute-type larvae, the gill apparatus is located at the posterior end of the abdomen in the form of three thin expanded plates, penetrated by a mass of tracheal tubes. Shortly before the adult dragonfly hatches, the larvae also begin to breathe atmospheric air using spiracles that open on the upper side of their chest. This explains why adult larvae often sit on aquatic plants, sticking the front end of their body out of the water.

Lute-type larvae have the ability to discard gill plates if they are pinched. This is easy to verify experimentally: place the larva in water and squeeze the gill plate with the tip of tweezers. This phenomenon is called self-mutilation (autotomy) and is well known in many animals (spiders, lizards, etc.). For this reason, it is necessary to catch larvae from the water that are missing 1 - 2, and sometimes all 3 tail plates. In the latter case, breathing occurs, in all likelihood, through the thin skin covering the body. The torn plate is restored again after some time, due to which larvae with gill plates of unequal length can be observed. It should be noted that in Calopteryx one of the plates is always shorter than the other two, which is not an accidental circumstance, but a generic characteristic.

Dragonflies reproduce using eggs that females lay in water. The clutches of different species are very diverse. Dragonflies of the rocker and lute type drill their eggs into the tissue of aquatic plants. In this regard, their eggs have a characteristic oblong shape, and the inserted end is pointed. In the place where the egg is stuck, a mark remains on the surface of the plant, which then takes the form of a dark spot or scar.
Since eggs different types dragonflies are located on the plant in in a certain order, then peculiar, sometimes very characteristic patterns are formed.

The suborder of dragonflies is Homoptera;

Lutka family; Lutka-bride.

A very slender, elegant, graceful dragonfly (see appendix, Fig. 28). The body is green, metallic-shiny. Females have yellow sides and breasts, while males have a bluish-gray coating.

There are no significant differences between dragonflies, and all descriptions of dragonflies and their larvae are the same, so in the previous chapter you can find all the descriptions of both larvae and adults.

Mayfly squad;

Common mayfly.

Quiet summer evenings when it no longer stings Sun rays, some insects similar to butterflies, but with two or three long threads on their tail, swarm in the air near the banks of rivers, lakes and ponds (see Appendix, Fig. 29). They either soar upward, then freeze, stabilizing the fall with long tail threads, then, spreading their wide wings, slowly fall down. So they swirl over the shore, like dense fog or a cloud about ten meters high and about a hundred meters long. These swarms rush over the water like a storm. You don’t see such an exceptional phenomenon every day, only in July-August it repeats several times.

This is what mayflies dance during their mating flight. Their wings and they themselves are so delicate that it is simply amazing how they do not break during flight. You can’t help but think that they won’t live long. And this opinion is correct: many mayflies live only one day. That's why they are called mayflies, and their scientific name comes from the Greek word "ephemeron" - quickly passing.

After the nuptial flight, the females lay eggs in the water and die. With such short life they don't eat anything.

Mayfly larvae develop in water. The larvae live longer, two to three years. And unlike adults, they eat very well. And they feed on algae, decaying organic matter, small invertebrates and molt up to twenty-five times during development. Many fish feed on mayfly larvae, and various birds eat adult mayflies.

Upon examination, the first thing that catches your eye is the fast, sharp movements of the larva. When disturbed, it rushes headlong and swims very briskly, with three feathery tail filaments, richly pubescent with hairs (C1oeon, Siphlurus), serving as fins. The legs serve mainly for attachment to aquatic plants. The fast movements of mayflies probably serve as protection from their many enemies, who actively hunt for these delicate larvae. The color of the larvae, generally greenish, matching the color of the aquatic plants among which they huddle, probably also plays a protective role.

The respiration of larvae is easy to observe during excursions. It is of considerable interest as good example tracheobranchial respiration. The gills look like thin, delicate plates that are placed in rows on both sides of the abdomen (Cloeon, Siphlurus). These delicate tracheal leaves are constantly moving, which can be clearly seen in a larva sitting in the water even without the help of a magnifying glass. Most often, these movements are uneven, jerky: as if a wave runs through the leaves, which then remain motionless for some time until a new wave occurs. The physiological significance of this movement is completely clear: in this way, the flow of water washing the gill plates is enhanced and the exchange of gases is accelerated. The larvae's need for oxygen is generally very high, so in aquariums the larvae die at the slightest spoilage of the water.
The diet of the larvae is very varied. Free-swimming forms living in stagnant waters, which are most often encountered on excursions, are peaceful herbivores, feeding on microscopic green algae (Cloeon, Siphlurus). Other species lead a predatory lifestyle and actively hunt for small aquatic animals. The food of many mayfly species is not yet well understood.

Reproductive phenomena in mayflies are of great interest and have long attracted the attention of observers. Unfortunately, you only see these phenomena on excursions by chance. As mentioned above, females drop their eggs into the water. The eggs hatch into larvae that grow and molt repeatedly (Cloeon has more than 20 molts), and the rudiments of wings gradually form in them. When the larva completes its development, a winged insect hatches. At the same time, the larva floats to the surface of the reservoir, the covers on its back burst, and in a few seconds an adult mayfly emerges from its skin and flies into the air. Since the hatching process of the larvae often occurs simultaneously, the surface of those reservoirs where the larvae are found in large numbers presents a remarkable spectacle during hatching, which has been described more than once in the literature: the surface of the water seems to boil from a multitude of hatching insects, and clouds of mayflies, like flakes of snow fluttering in the air. However, winged insects that hatch from larvae do not represent the final stage of development. They are called subimago and after a short period of time (from several hours to 1-2 days) they molt again, thus turning into imago (the only case among insects of winged molting). Sometimes on an excursion you can observe how a winged mayfly lands on some plant or even on a person and immediately sheds its skin.

Squad pincers;

family hydrachnids;

The vast majority of ticks are very small animals, no more than one millimeter, only a few are larger, for example, our tick.

Family representative freshwater mollusks group of gray-eyed people. It has an elongated, strongly pointed shell 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 containing a mass of vessels and serving 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. Placed right here long tongue, which rake in 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.
The snail reaches large sizes, and therefore is not entirely convenient for an aquarium. This inconvenience is increased by the fact that it grows so quickly and a 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.
Also belongs to the same genus of pond snails Limnea stagnalis (common pond snail), even larger than the above.

Gastropods are the most numerous and diverse group of mollusks. It has about 90,000 species living in the seas, fresh water bodies, and on land. Most of them have a one-piece shell.

One of the representatives of this class lives in lakes, ponds and river backwaters - big pond snail about 5 cm in size.

External structure

In the pond snail, all three parts of the body are clearly visible: the head, the leg and the bag-like body. The top of the body is covered with a mantle. The pond snail has a spiral shell, twisted in 4-5 turns, which protects the body of the animal. The shell consists of lime, and is covered on top with a horn-like organic matter. Due to the spiral shape of the shell, the body of the pond snail is asymmetrical, since in the shell it is also curled into a spiral. The shell is connected to the body by a powerful muscle, the contraction of which pulls the animal inside the shell.

The pond snail's leg is well developed, muscular, and has a wide sole. The animal moves slowly by sliding over plants or soil due to the wave-like contraction of the leg muscles. The copious mucus secreted by the skin glands of the leg facilitates smooth gliding.

Internal structure

Digestive system

In the mouth, on a special movable outgrowth resembling a tongue, there is a grater with horny teeth. With their help, the pond snail scrapes off the soft parts of plants and microscopic algae deposits on underwater objects. There are in the pharynx salivary glands, the secretion of which processes food.

From the pharynx, food enters the stomach through the esophagus. The liver ducts flow into it. The stomach passes into the intestine, which makes several loops and ends with the anus at the anterior end of the body above the head.

Respiratory system

The body of the animal is covered on the outside with a mantle and is closely adjacent to the inner surface of the shell. Part of the mantle forms a kind of lung; numerous blood vessels develop in its walls, and gas exchange occurs here. The pond fish is breathing atmospheric oxygen, so it often rises to the surface of the water and opens a round breathing hole on the right at the base of the shell. Next to the lung is the heart.

Circulatory system

The circulatory system is not closed, the blood is colorless. The heart consists of two sections - the atrium and ventricle, and blood vessels. Blood flows not only through the vessels, but also in the cavities between organs. A large vessel departs from the heart - the aorta. It branches into arteries. The blood then enters the small cavities among connective tissue. There the blood gives off oxygen and becomes saturated carbon dioxide, enters the veins and travels along them to the lungs.

Here the veins branch into numerous small vessels - capillaries. The blood is enriched with oxygen and gets rid of carbon dioxide. Blood rich in oxygen is called arterial, and blood poor in oxygen and rich in carbon dioxide is called venous. The blood then collects in the veins and enters the heart. It contracts 20-40 times per minute.

Excretory system

Due to the asymmetry of the body, the pond snail retains only the left kidney.

At one end, through a wide ciliated funnel, it communicates with the pericardial sac, where waste products accumulate, and at the other, it opens into the mantle cavity on the side of the anus.

Nervous system

The nervous system of mollusks is of the scattered-nodular type. It consists of five pairs of nerve ganglia (ganglia), interconnected by nerve bridges, and numerous nerves.

Due to the twisting of the body, the nerve bridges between some nodes form a cross.

Sense organs

The pond snail's head contains organs of touch - tentacles; there are also tactile cells in the skin. The pond snail has one pair of tentacles. There are eyes - they are located at the base of the tentacles. There are also organs of balance.

Reproduction. Development

Fertilization in the pond snail is internal. This animal is hermaphrodite. A single gonad produces both sperm and eggs. They reproduce by eggs, which are laid on aquatic plants or other objects. Fertilized eggs are covered with a common mucous membrane and are securely attached to the substrate. Each animal lays about twenty clutches during the year.

After about twenty days, tiny animals emerge from the eggs. They grow quickly, eating plant foods.

The pond fish becomes sexually mature at the end of the first year of its life. It is also interesting that when the reservoir (in which pond snails live) dries out, not all mollusks die. Some secrete a dense film that closes the opening of the shell. In this state, a pond snail can live without water for about two weeks.