Where does the pond snail live and what does it eat? Subclass Pulmonata Common pond snail

From early spring to late autumn In stagnant and slow-flowing reservoirs you can find snails from the large family of pond snails. The common pond snail is the largest and most common of them.

More than 100 species of this family are known, and in our country there are several dozen species, most of which belong to the genus of pond snails. The common pond snail, or pond snail, is the most common and widespread in Africa, North America, Europe and Northern Asia to Kamchatka.

TURBISH GLUTTER

The appearance of the pond snail is very variable: depending on the living conditions, the color, shape and size of the shell and body vary. In this regard, several geographical subspecies are distinguished.

Pond fish are common inhabitants of ponds, lakes, river backwaters, canals and other bodies of water with abundant vegetation. They live well even in brackish water. These are large gluttons, eating both living and rotting plants, and sometimes insects and fish eggs that have fallen into the water.

The mollusk spends most of its life crawling among the thickets at a speed of 30 cm to 1 m per hour and scraping algae and small animals from the underside of the leaves.

For this he has oral cavity There is a special device - a grater, or radula. This is a tongue with many sharp horny teeth. Sometimes pond snails swallow sand, which, remaining in the stomach, helps digest food.

Common pond snails can also be found in swamps and puddles with rather dirty water, although they do not live in rotting water. Snails can survive without water for up to two weeks if their pond is dry. In this case, they have mucus that hardens in the air, which, like a lid, reliably seals the shell with the owner drawn into it.

But lake dwellers do not have a real operculum, like some mollusks. Even after spending some time frozen in the ice, the pond snail can come to life after thawing.

FEET UP

A long time ago, the aquatic ancestors of pond snails breathed with gills, and then came to land and acquired lungs, more precisely, an azygos lung - a respiratory cavity formed by a fold of skin. Later they returned to an aquatic lifestyle, but did not change their pulmonary breathing. Periodically, usually 6-9 times per hour, pond snails rise to the surface to renew the air in the pulmonary cavity, and expose the muscular edge of the mantle rolled into a tube, forming a breathing hole on the side, near the edge of the shell. But if necessary, the pond snail may not rise to the surface for quite a long time, about an hour, sparingly consuming air. In this case, pulmonary respiration is partially replaced by cutaneous respiration. Having risen to take a breath of air, the snails slowly crawl along the underside of the surface film of water, leaving behind a slimy trail. This is possible thanks to the wide sole and air-filled breathing cavity. If you push such a snail, it, having plunged into the water, rises again like a float. But the mollusk can also compress the lung, releasing an air bubble, if it wants to dive deeper.

CRADLE FOR SNAIL

Like all gastropods, the common pond snail is a hermaphrodite, that is, each individual has both female and male genital organs. But he has cross-fertilization. To lay viable eggs, pond snails mate from early spring to late autumn, except in frosty weather. winter months, which are spent in a state of torpor at the bottom of the reservoir. Double-shelled eggs (from 20 to 130 pieces) are immersed in a mucous mass and suspended from the wall of the surrounding capsule, or cocoon. Overall, this design looks like a transparent slime cord attached to underwater objects. Each egg in such a cord is protected and provided with protein material for the development of the embryo. Perhaps this method of caring for offspring was inherited by pond snails from their land-dwelling ancestors, for whom it was important that the eggs did not dry out. After 20 days, small snails with a thin shell emerge from the eggs, which grow quite quickly, feeding on plant foods, and at the end of the first year of life they are ready to become parents themselves, although they still only reach half their normal size.

Representatives of some species of pond snails living in deep lakes have adapted to live at great depths. Under these conditions, they are no longer able to rise to the surface to capture atmospheric air; their pulmonary cavity is filled with water, and gas exchange occurs directly through it. This is only possible in clean, oxygen-rich water. Such mollusks are usually smaller than their shallow-water counterparts.

A BRIEF DESCRIPTION OF

Type: shellfish.
Class: gastropods.
Family: pond snails.
Genus: pond snails.
Species: common or large pond snail or pond snail.
Latin name: Limnaea stagnalis .
Size: sink length - 68-70 mm, width - 27 mm.
Color: shell brown, brown, leg and body from blue-black to sandy yellow.
Life expectancy of a pond snail: on average about a year, up to 2 years.

Big pond snail - inhabitant of fresh water bodies. It has a cone-shaped, spirally twisted shell with 4-5 curls, a sharp apex and a large opening - the mouth. The shell serves as protection for the soft parts of the mollusk’s body; muscles are attached to it from the inside. The shell consists of lime covered with a layer of greenish-brown horn-like substance. In body pond snail three main parts can be distinguished: torso, head and leg, but there are no sharp boundaries between them. Through the mouth, the front part of the body and the leg protrude out. leg pond snail muscular. When wave-like muscle contractions run along its sole, the mollusk moves. Leg pond snail located on the ventral side of the body (hence the name of the class - gastropods).

The body follows the shape of the shell, closely adhering to its inner surface. On the outside it is covered with a fold of skin - the mantle. In front, the body meets the head. A mouth is placed on the underside of the head, and two sensitive tentacles are located on its sides. When touched, the mollusk quickly pulls its head and leg into the shell. There are eyes near the base of the tentacles on the head.

Features of life processes: Prudovik feeds on aquatic plants. In his throat is a muscular tongue covered with hard teeth. Prudovik From time to time it sticks out its tongue and scrapes it, like a grater, with the soft parts of plants, which it swallows. Through the pharynx and esophagus, food enters the stomach and then into the intestines. The intestine bends in a loop inside the body and ends near the edge of the mantle with the anus. Unlike all previously studied animals at pond snail There is a digestive gland, the liver, whose cells produce digestive juice. Thus, digestive system pond snail more difficult than that of an earthworm.

Breathing is pulmonary. Periodically rising to the surface of the water, it fills the mantle cavity with fresh air through a round breathing hole. The walls of the lung are densely intertwined with blood vessels; here the blood is enriched with oxygen and carbon dioxide is released. Within an hour, the mollusk rises to breathe 7-9 times. Next to the lung is the muscular heart, consisting of two chambers - the atrium and the ventricle. Their walls alternately contract (20-30 times per minute), pushing blood into the vessels. Large vessels turn into thin capillaries, from which blood flows into the space between the organs. Thus, unlike annelids The circulatory system of the mollusk is not closed, since it communicates with the body cavity and blood does not flow through the vessels all the time. From the body cavity, blood collects in a vessel that approaches the lung, is enriched with oxygen and enters the atrium. Blood pond snail colorless. The excretory organs are represented by one kidney. Main part nervous system pond snail constitutes a peripharyngeal cluster of nerve ganglia. Nerves extend from them to all organs of the mollusk.

Reproduction: Hermaphrodite. Postpones a large number of eggs enclosed in transparent mucous cords. Which are attached to underwater plants. The eggs hatch into small mollusks with a thin shell.

In ponds, lakes and quiet river backwaters, you can always find a large gastropod snail on aquatic plants - common pond snail.

Structure

The body of the pond snail (Fig. 58) is enclosed in a spirally twisted shell of 4-5 turns, which has a sharp apex and a large opening - the mouth. The shell consists of lime, covered with a layer of greenish-brown horn-like substance and reaches a height of 45-55 mm. It serves as protection for the soft body of the pond fish.

Three main parts can be distinguished in the body of a pond snail: the body, head and leg, but there are no sharp boundaries between them. Only the head, leg and front part of the body can protrude from the shell through the mouth. The leg is muscular and occupies the entire ventral side of the body. Mollusks that have legs like those of a pond snail are called gastropods.

The sole of the foot secretes mucus, with the help of which the foot glides over underwater objects or even over a surface film of water, suspended from below, the pond fish smoothly moves forward.

The body follows the shape of the shell, fitting closely to it. In the front part of the body is covered by a special fold - the mantle. The mantle (fold of skin) and the shell, twisted in a spiral, form the cover of the pond snail. The space between the body and the mantle is called the mantle cavity, through which communication with the external environment occurs. In front, the body meets the head. A mouth is placed on the underside of the head, and two sensitive tentacles are located on its sides. When touched, the pond snail quickly pulls its head and leg into the shell. There is an eye near the base of the tentacles.

Digestive system

The common pond snail is a herbivore. The mouth leads to the throat. It contains a muscular tongue covered with teeth - this is the so-called grater. With it, the pond snail scrapes off deposits of organic matter that form on underwater objects, or scrapes the soft parts of plants. In the pharynx, food is processed by secretions salivary glands. From the pharynx, food enters the stomach, then into the intestines. Digestion of food is also facilitated by a special digestive gland - the liver. The intestine ends with the anus, located above the head.

Respiratory system

Although the pond snail lives in water, it breathes atmospheric air. To breathe, it rises to the surface of the water and opens a round breathing hole at the edge of the shell (Fig. 58), through which it enters atmospheric air. It leads into the cavity - the lung, formed by the mantle and penetrated by a network of blood capillaries. In the lung, the blood is enriched with oxygen and carbon dioxide is released.

Circulatory system

The circulatory system of the pond snail (Fig. 58) is represented by a two-chambered heart, consisting of an atrium and a ventricle, and blood vessels.

Arterial blood flows from the lung to the atrium, then to the ventricle, and from there it moves through the vessels to all organs of the body and pours out between them. Such a circulatory system is called open. Having given up oxygen and enriched with carbon dioxide, the blood collects in the venous blood vessels and enters the lung, where gas exchange occurs again. Oxygenated blood moves through the vessels to the heart. It is more difficult to ensure the movement of blood in an open circulatory system than in a closed one, since in the spaces between organs the movement of blood slows down. The voluminous two-chambered heart serves as a pump that pumps blood.

Excretory system

The excretory system of the common pond snail (Fig. 58) includes one kidney with a ureter that comes off near the anus.

The kidney has a direct connection with the circulatory system and absorbs the end products of protein breakdown from the blood.

Nervous system

The nervous system of the pond snail is of a nodal type and includes a peripharyngeal nerve ring formed by two nodes and four pairs of nodes with nerves extending from them. Material from the site

Sense organs

The pond snail has organs of vision under the tentacles - eyes, organs of touch - tentacles and organs of balance - small whitish vesicles lying on the surface of the nerve ganglion of the legs. In these bubbles in a liquid environment there are small bodies, changing the position of which allows you to maintain the balance of the body.

Reproduction

Reproduction is sexual. Common pond snails- hermaphrodites. Fertilization is internal.

During copulation of two individuals, mutual fertilization occurs, that is, exchange male gametes- spermatozoa. After this, the individuals disperse and lay fertilized eggs tied into gelatinous cords. They attach to underwater plants.

From the zygote small pond snails with a thin shell develop.

Position in taxonomy (classification)

The common pond snail is one of the species of the most numerous class of mollusks - Gastropods.

On this page there is material on the following topics:

• Common pond snail mollusks taxonomy in Latin

• How to draw the excretory system of a pond snail

• Report on the common pond snail

• Pond snail shell structure

• The structure and significance of the pond snail shell

Questions about this material:

• Hello, dear friends!

  Pond snail (Limnaea)

  Meet Limnaea or pond snail! A gastropod, native to Europe, Asia, and North America.
  

  The main difference between the pond snail and some other species gastropods consists not only of appearance. The fact is that this mollusk breathes not with gills, but with lungs! Therefore, it can often be found on the surface of the aquarium.

  The appearance of the pond snail is as follows: the snail has an elongated, rounded shell shape.

  The top of the shell is pointed and has a right slope. Size of the mollusk: it grows up to 50 millimeters in height, and the total diameter of the shell is up to 28 millimeters. As you can see, friends, this is a rather large freshwater snail.

  The pond snail also has eyes, which are located on the outside of its triangular, flat tentacles. The “leg” is relatively short, but quite wide. Basic color: the body of the mollusk itself is gray or grayish-green, and the shell is yellow, light yellow or dirty yellow. This snail is not picky about water quality!

  As for food, the pond snail, like many species of gastropods, is omnivorous. It eats the remains of fish food and their waste products, and loves fallen parts that begin to rot. These snails are also scavengers and can utilize dead fish that have begun to decompose. There is only one “minus” about these mollusks - their insatiable, simply wild appetite! They are constantly eating! They love it very much succulent plants, so keep that in mind, friends! Therefore, I highly recommend planting plants with hard leaves, such as pondweed, in the aquarium: these snails do not like hard plants.

  As for the reproduction of pond snails, everything is somewhat simpler for them than for other species. The fact is that pond snails are hermaphrodite mollusks! At a certain period, these snails hang their eggs on the tips of plant leaves. Such icicle cocoons are quite easy to spot. Each cocoon contains up to hundreds of eggs. The entire clutch matures within 25-30 days.

  This is such an interesting snail! There is controversy over keeping pond snails in an aquarium. Some argue that this is an evil mollusk that, apart from trouble, brings nothing more to the aquarium. Others simply do not recommend placing it in an aquarium. In general, how many people - so many opinions! The main thing is to regulate their quantity and that’s it! Remove snail eggs from . Moreover, the time to detect the eggs of this snail is almost a whole month!

  With this I say goodbye to you, dear friends! All the best to you and see you soon!

  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.

  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.