What does the small pond snail eat? Small prudovik

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 external environment. 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 atmospheric air enters. It leads into the cavity - the lung, formed by the mantle and penetrated by a network of blood capillaries. In the lung, blood is enriched with oxygen and secreted carbon dioxide.

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 are hermaphrodites. Fertilization is internal.

During copulation of two individuals, mutual fertilization occurs, that is, the exchange of male gametes - sperm. 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:

Brief message about the pond snail
Does the common pond snail secrete mucus?
Type of circulatory system of the pond snail
Adaptation of mollusks to the habitat of the common pond snail
Pond grater

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 succulent plants, so keep this 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!

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, from dark blue to yellow flowers. 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 to the globe, mainly on ponds, rivers, lakes, etc. They live at shallow depths.

The pond snail family includes well-known freshwater lung mollusks that are widespread throughout the world.

From large number Among the species belonging to this family, the common pond snail is best known for its large size, the largest specimens of which reach 7 centimeters. WITH early spring before 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 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. Even though they are aquatic organisms, but, like all pulmonary mollusks, they breathe with with the help of the lung and are forced to rise to the surface to “take a breath” of 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. Complex structure egg laying is also typical for other freshwater lung molluscs. 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 eggs of pond snails 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 large representatives, almost dwarf forms are known, undergrown due to unfavorable conditions and malnutrition. 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 because they life cycle ends in one season.

Molluscs, or soft-bodied mollusks, live in the sea, in fresh waters and on land. The body of mollusks is usually covered with a shell, under which there is a fold of skin - the mantle. The space between the organs is filled with parenchyma. About 100,000 species of mollusks are known. We will get acquainted with representatives of three classes: gastropods, bivalves and cephalopods.

Lifestyle and external structure. In ponds, lakes and quiet river backwaters you can always find a large snail on aquatic plants - large pond snail. On the outside, the pond snail's body is covered with a protective spirally twisted shell about 4 cm long. The shell consists of lime, covered with a layer of greenish-brown horn-like organic matter. The shell has a sharp apex, 4-5 whorls and a large opening - the mouth.

The pond snail's body consists of three main parts: head, torso and legs. Only the leg and head of the animal can protrude from the shell through the mouth. The pond snail's leg is muscular. When wave-like muscle contractions run along its sole, the mollusk moves. The pond snail's leg is located on the ventral side of the body, and therefore it is classified as a gastropod. In front, the body meets the head. A mouth is placed on the underside of the head, and two tentacles are located on its sides. The pond snail's tentacles are very sensitive: when you touch them, the mollusk quickly retracts its head and leg into the shell. There is an eye near the base of the tentacles on the head.

The body follows the shape of the shell, closely adhering to its inner surface. The outside of the body is covered with a mantle, with muscles and parenchyma located underneath it. Inside the body there remains a small cavity in which the internal organs are located.

Nutrition. The pond fish feeds on aquatic plants. In his mouth is a muscular tongue covered with hard teeth. The pond fish from time to time sticks out its tongue and scrapes off the soft parts of plants with it, like a grater, 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 on its right side, near the edge of the mantle, with the anus. Next to the stomach in the body cavity lies a grayish-brown organ - the liver. Liver cells produce digestive juice, which flows through a special duct into the stomach. Thus, digestive system The pond snail is even more complex than that of the earthworm.

Breath. Despite the fact that the pond snail lives in water, it breathes oxygen atmospheric air. To breathe, it rises to the surface of the water and opens a round breathing hole on the right side of the body at the edge of the shell. It leads to a special pocket of the mantle - the lung. The walls of the lung are densely intertwined with blood vessels. This is where the blood is enriched with oxygen and carbon dioxide is released. Within an hour, the mollusk rises to breathe 7-9 times.

Circulation. 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, circulatory system unclosed mollusk. The blood is then collected in a vessel that approaches the lung. Here it is enriched with oxygen and flows through the vessel into the atrium, and from there into the ventricle. Pond snail blood is colorless.

Selection. The pond snail has only one excretory organ - the kidney. Its structure is quite complex, but general outline resembles the structure of the excretory organs of an earthworm.

Nervous system. Main part nervous system The pond snail is a peripharyngeal cluster of nerve ganglia. Nerves extend from them to all organs of the mollusk.

Reproduction. Pond fish are hermaphrodites. They lay masses of eggs enclosed in transparent slimy cords that attach to underwater plants. The eggs hatch into small mollusks with a thin shell.

Other gastropods. Among the large number of gastropod species, marine mollusks are especially famous, thanks to beautiful shells. Slugs live on land, so called because of the abundant mucus they secrete. They don't have shells. Slugs live in damp places and feed on plants. Many slugs eat mushrooms, some are found in fields and gardens, causing damage to cultivated plants.

Widely known grape snail, which is used as food in some countries.