Common pond snail mollusk. Type of shellfish. Class Gastropods. Big pond snail. The structure of a large pond snail

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, 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 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 in the pond snail

• Adaptation of mollusks to the habitat of the common pond snail

• Pond grater

Questions about this material:

• Pond snails are gastropods.

  The largest of the domestic representatives of the pond snail family (Limnaeidae) - common pond snail (Limnaea stagnalis), having an elongated conical shell up to 55 mm high. U eared pond snail (L. auricularia) shell with a short curl, resembling an ear (height 26 mm). Marsh pond snail (L. palustris) similar to the common one, but its shell has the shape of a sharp cone with a small hole (shell height 32 mm). Sink egg-shaped pond snail(L. ovata) with a short whorl, and its last whorl with a wide ovoid opening (shell height 18 mm).

  Pond fish live in freshwater bodies of water. The common pond snail is especially widespread. It stays near the surface of the water and is easy to catch. In the jar, it slowly crawls along the walls of the vessel. SlipperThis occurs due to the fact that the muscles of the sole of the wide leg contract in a wave-like manner.

  Ponds: 1— ordinary; 2 - ear; 3 - swamp; 4 - ovoid

  

  Pond snail structure: 1— oral lobes; 2— tentacles; 3— eyes; 4 - leg; 5— breathing hole

  Pond snails can wander along the underside of the surface film of water, holding onto it with the help of their soles. At the same time, a ribbon of mucus remains behind them. It is believed that this movement is due to the surface tension of water.

  The pond snail has air inside its respiratory cavity, which, like the swim bladder of a fish, supports it. If you give a slight push to a crawling snail, it will submerge in the water and float up again, like a cork. The cochlea can arbitrarily compress the respiratory cavity and, due to a decrease in specific gravity, sink to the bottom; when the cavity expands, it floats to the surface.

  Pond fish are capable of staying underwater for very long for a long time. This is explained by the fact that the closed lungIn this cavity, air is used very rationally during breathing, and oxygen is gradually replaced by carbon dioxide. In addition, it is likely that respiration also occurs through the skin, using oxygen dissolved in water.

  

  Pond snails feed on leaves and stems aquatic plants. Therefore, individuals large species cannot be planted in a decorative aquarium. In addition to plants, they eat small organisms (hydra, protozoa), fish eggs, meat and even the remains of dead fish and snails. So it is better to keep pond snails in a separate container.

  When breeding, these snails lay eggs on aquatic plants and other objects. The masonry has the appearance of a transparent gelatinous sausage. In twenty daysThe eggs hatch into tiny snails that feed plant foods, grow quite quickly. This whole process can be observed in the aquarium.

  

  All pond snails, like most gastropods, hermaphrodites.

  More interesting articles

  In this article we will look at who the pond snail is, what features it has, where it is found and much more about this wonderful mollusk. What types of pond snails exist and what they look like.

  Any from pond snails, whether ordinary, small or large, is a snail that lives in ponds and gardens where there is enough moisture.

  Large and small pond snail

  The large pond snail belongs to the class of gastropods, which is the most numerous and diverse compared to other classes of gastropods. There are more than 90 thousand species of such mollusks in nature, and their habitat is not only ponds, but also the sea and land.

  The large pond snail is about 5 cm long and has many distinctive features from brothers.

  Let's talk about the external structure of a large pond snail. It consists of three parts that are noticeable and clearly distinguishable from each other. The body outside the shell is covered with a mantle to protect the internal mucous membrane; the shell of the mollusk is twisted for convenience into a spiral of 5 turns. This structure of the shell provides reliable protection of the body from irritants and mechanical damage. . The sink contains lime for the basis of the structure of the spirals, and on top it is covered with an organic substance of a horn-like type (this is found on the horns of cattle, etc.).

  Due to the structure of the shell, it received an asymmetrical body to better fit into the “protection”; the shell is connected to the body by a muscle. The muscle allows the animal to be pulled inside the shell, and with the help of a pronounced leg, the mollusk can crawl back out.

  In internal structure For pond snails of any type, everything is arranged simply. The main organs are:

  1. digestive complex;
  2. leg;
  3. eyes;
  4. excretory and respiratory system;
  5. sole and mucus secretion glands.

  The snail feeds on plant food in crushed form, then the food from the tongue (has a “grater”) passes into the pharynx, is processed by the secretion of splitting and processed in the stomach and intestines.

  The circulatory system is not closed, and mollusks move due to powerful legs, which glides over any surface thanks to the secretion secreted by the glands.

  These animals are unique and there is no need to kill them. . They don't harm anyone, nor gardens, because they feed on plant foods that are easily processed (that is, weeds such as ephemerals (wheatgrass, woodlice). Snails also have healing properties, they are at proper nutrition and application secrete mucus that nourishes human skin and produce regeneration of epithelial cells.

  Small pond snail

  Who are pond snails? in general, you know from the previous paragraphs, now we will talk about small things. There are several small pond snails in nature:

  

  Small snails are found in all gardens, are small in size and beautiful in appearance. Be kind to snails, they do no harm, more good.

  Common pond snail

  The common pond snail is found in middle lane– Russia, Europe. The pond snail is large in size, one shell is 7 cm, not including the body. The pond snail breathes with nothing more than miniature lungs, the circulatory system is not closed, and they feed on tough plant foods, detritus and midges. External structure does not differ from a large pond snail, except that the body does not always correspond to the size of the shell, sometimes smaller than the shell. The color of the shell is pearlescent brown. Body color – brown, gray, white.

  Snails can easily survive both in nature and in the artificially created environment of a terrarium or aquarium. The snail moves thanks to the secretion of mucus and the outer sole, which allows it to move quite quickly over various distances. Snail mucus is rarely used in cosmetology, but most often the mollusk is used for decoration.

  Mollusks become attached to people - breeders, so if you fall in love with a snail, do not give it to others, otherwise the animal’s weak heart will not stand it.

  Now let's take a look at the photo of the pond snail

  Great pond snails

  

  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.

     Class - Gastropods
     Row - Basommatophara
     Genus/Species - Lymnaea stagnalis

     Basic data:
  DIMENSIONS
  Shell length: 45-70 mm.
  Shell width: 20-30 mm.

  REPRODUCTION
  Mating season: spring or summer when the water warms up.
  Type of reproduction: pond snails are hermaphrodites.
  Number of eggs: 200-300 eggs in cords attached to underwater objects. The eggs hatch into miniature versions of the adults.

  LIFESTYLE
  Habits: They stay solitary in stagnant bodies of water and slow-flowing rivers.
  Food: organic waste and algae, sometimes carrion.
  Lifespan: 3-4 years.

  RELATED SPECIES
  The pond snail family includes about 100 species, for example, long-eared, marsh and small pond snails.

     The ordinary pond snail lives in water, but breathes atmospheric air. That is why it can inhabit reservoirs with stagnant water, which contains a minimal amount of oxygen. In such swamps and lakes there is a lot of rotten plant and animal remains - the main food of the common pond snail.
  

  REPRODUCTION

     Pond fish are hermaphrodites. Each individual has both male and female reproductive organs. Despite this, during mating, both partners mutually fertilize each other. Later, pond snails lay eggs in long dragnet cords. The cords are attached to underwater parts of plants and rocks. Sometimes they even stick to the shells of other individuals. Pond snails do not have a free-swimming larval stage. Each egg develops into an embryo, which, after emerging from the shell, looks like a smaller copy of the adult.

  LIFESTYLE

     Many snails that live under water breathe using thread-like gills. The gills of these cephalopods contain many blood vessels. Animals get oxygen directly from water. However, in the common pond snail, the respiratory organs have the form of pulmonary sacs. The mantle cavity of these cephalopods, which is connected to the external environment only through a small respiratory opening by a pneumostome, penetrated by a dense network of small blood vessels. It acts like the human lungs. The disadvantage of this type of breathing is the need to surface approximately every 15 minutes in order to replenish air reserves. However, thanks to this respiratory organ, the pond snail can live in water bodies with low oxygen content.
     The pond snail can move freely from the underside of the surface film of water. This is possible due to the fact that with the help of the lungs the mollusk scoops up a large number of air, which lifts it to the very surface.
  

  FOOD

     In stagnant water, organic substances and microorganisms settle on submerged tree trunks or stems of aquatic plants, which contribute to their decomposition. Pond snails eat this layer of organic debris, waste, bacteria, protozoa, blue-green algae and mud. These mollusks are omnivores. The snail also feeds on the eggs and larvae of other aquatic animals, and also attacks wounded fish, tadpoles or newts.
     With the help of the radula, pond snails eat the leaves of water lilies and scrape algae from the lower surface of the leaves of water lilies. The radula of gastropods resembles a sharp file, which is constantly renewed, since it wears off quite quickly. The anterior worn teeth on the radula are periodically replaced by new sharp teeth. The basis of the radula is chitin - chemical compound, which is contained in the strong shells of insects. The pond snail's radula acts like a grater. Carnivorous snails use the radula to make a hole in the shell of other mollusks and get inside. At unfavorable conditions the growth of pond snails stops.
  

  OBSERVING THE PRODUCER

     Common pond fish are found in ponds, lakes or rivers. They can only live in hard water. From hard water, pond snails obtain lime, which they need to build their “house” and shells. In areas where the main rock is limestone or similar sedimentary rocks, pond snails can live almost anywhere: in small lakes, ponds, water-filled ditches, irrigation canals and rivers. Common pond snails can be placed in aquariums, where they slowly travel along the glass and scrape off a layer of algae from it with their radula. These gastropods can swim near the surface on the underside of the water film. The disturbed pond snail “falls” to the bottom.
    

  DID YOU KNOW THAT...

  • The shape of the common pond snail shell depends on the location of the particular individual. These mollusks are extremely variable; not only their size, color, shape, but also the thickness of the shell varies.
  • The small pond snail is one of the smallest representatives of the family. It lives not only in reservoirs, but also in flooded meadows and pastures. The small pond snail is intermediate host liver fluke, which causes fascioliasis in sheep and cattle.
  • Shells of all European species pond snails twisted to the right. Only as an exception are there individuals with left-handed (leotropic) shells.
    

  FEATURES OF THE COMMON PONDOWER

     Horn Coil: a close relative of the pond snail lives in the same habitat. However, it is much smaller than the pond snail, and in addition, it has a shell of a different shape. Sometimes you can see a horn-like coil that is attached to the shell of a common pond snail.
     Tentacles: grow on the sides of the head, they are flattened and triangular, which markedly distinguishes them from the thread-like tentacles of other types of snails. The tentacles perform only the function of an organ of touch. The eyes are located at their base.
     Sink: ends with a long tip. It consists of lime and is covered with a yellowish stratum corneum. It is quite thin and easily damaged.
     Eggs: The pond snail deposits in long drag-like cords, which are glued to various underwater objects. The number of eggs in a clutch varies between 200-300 pieces. The eggs are surrounded by a mucous mass, which is dressed like a special capsule, or cocoon. Hatched from eggs to look like miniature versions of their parents.
  
  PLACES OF ACCOMMODATION
  The pond fish lives in ponds with stagnant water and in rivers with a slow flow. It is found in Central, Western and Southern Europe, South-West Africa and Asia Minor, and from there the range of the pond snail reaches South-West India.
  PRESERVATION
  The prudovik is not in danger of extinction, but they are currently being polluted by the natural environment.

  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 of gastropods is not only 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!