The small pond snail breathes with help. Aquarium snail - pond

In this article, we will consider who a 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 do 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

The large pond snail belongs to the class 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.

A large pond snail is about 5 cm long and 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 perfectly distinguishable from each other. The body outside the shell is covered with a mantle to protect the internal mucosa, the shell of a mollusk is twisted for convenience in a spiral of 5 turns. This structure of the shell provides reliable protection of the body from irritants, mechanical damage. . The sink contains lime for the basis of the structure of spirals, and on top of it is covered with an organic substance of a horn-like type (such is on the horns of cattle, etc.).

Due to the structure of the shell, he received an asymmetric body for better accommodation in the "protection", the connection of the shell with the body is carried out due to the muscle. The muscle ensures that the animal is drawn into the shell, and with the help of a pronounced leg, the mollusk can crawl back.

In the internal structure 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 a crushed form, then food from the tongue (has a “grater”) passes into the throat, is processed by the secretion of splitting and processed in the stomach and intestines.

The circulatory system is open, and the molluscs move due to the powerful leg, which glides over any surface thanks to the secret secreted by the glands.

These animals are unique and do not need to be killed. . They don't harm a person, nor gardens, because they feed on plant foods that are easily processed (that is, weeds such as ephemera (wheatgrass, wood lice). Also, snails have healing properties, they proper nutrition and application secrete mucus that nourishes human skin and produce regeneration of epithelial cells.

Small pond snail

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

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

common pond snail

There is an ordinary pond snail in middle lane- Russia, Europe. The pond snail has a large 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, they feed on hard 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. Shell color - mother-of-pearl, brown. Body color - brown, gray, white.

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

Mollusks are attached to people - breeders, so if you fell in love with a snail, then do not give it to others, otherwise the weak heart of the animal will not stand it.

And now let's take a look at the photo of the pond

Snails big pond

The shell is spirally twisted, without a lid. In some species (slugs), the shell is reduced. Ganglia are concentrated in the head section, forming a peripharyngeal nerve ring. A nerve branch departs from the right parietal ganglion to an additional unpaired ganglion. Pulmonary mollusks have one atrium, one lung, and one kidney.

rice. one.
A - top view, B - side view: 1 - mouth, 2 - cerebral ganglion, 3 - pleural ganglion,
4 - parietal ganglion, 5 - visceral ganglion, 6 - liver, 7 - pericardium, 8 - lung, 9 - heart, 10 - kidney, 11 - stomach, 12 - sex gland, 13 - mantle cavity, 14 - leg, 15 - head, 16 - anus, 17 - additional unpaired ganglion.

(Fig. 2) - one of the largest terrestrial mollusks in Europe. The spherical-twisted shell has 4-4.5 whorls, reaches a height of 5 cm, a width of 4.5 cm. The shell is usually yellowish-brown in color with dark brown stripes running along it. The color and width of the stripes vary. On the head of a grape snail there are two pairs of tentacles, on one of which there are eyes, the other serves as organs of smell and touch. It feeds on the green parts of plants. By eating the leaves and buds of the vine, it can harm vineyards.

rice. 2. Grape
snail (Helix pomatia).

Grape snail is a bisexual animal. It has one hermaphroditic gland, in which female and male gametes are formed. A hermaphroditic duct departs from the gland, into which the protein gland flows. After the confluence of the protein gland, the hermaphroditic duct expands, forming two grooves: a wide one for eggs and a narrow one for spermatozoa. Further, each of the gutters is converted into independent channels, respectively, the oviduct and the vas deferens. The oviduct flows into the uterus, the uterus into the vagina. In addition to the oviduct, the ducts of the seminal receptacle and bags with calcareous needles flow into the uterus. The vagina opens with a genital opening in a special skin invagination - the genital atrium. The vas deferens passes into the ejaculatory canal, penetrating the copulatory organ, which opens into the genital atrium. During mating, grape snails exchange spermatophores (packages of sperm), which are captured by the sperm receptacles. Fertilization will occur after mating. The eggs that enter the uterus are fertilized by foreign spermatozoa coming from the seminal receptacle. The formed eggs are laid in a mink, which the parent individual previously digs in the soil with its muscular leg.

In a number of European countries, grape snails are used for food.

rice. 3. Big
pond snail (Limnea stagnalis).

(Fig. 3) and small pond snail (L. truncatula)- often found inhabitants of our fresh water bodies. The head bears one pair of tentacles, at the base of which are eyes. Hermaphrodites. During mating, just like in a grape snail, sperm is exchanged, and the fertilization of eggs is carried out by foreign sperm. They lay their eggs in slimy cords that are attached to underwater plants and other objects. Development is direct, without a larval stage. They breathe atmospheric oxygen, so they periodically rise to the surface of the water in order to gain a portion of air.

The size of the shell, its shape, and the color of the legs and body are characterized by strong variability in the large pond snail. For example, the color of the torso and legs can vary from blue-black to sandy yellow. The length of the shell of a large pond snail can reach 7 cm. The large pond snail is omnivorous, it feeds not only on plants and small animals, but can eat dead plant remains and animal corpses.

rice. four.
A - arion rufus (Arion rufus),
B - limax maximus
(Limax maximus).

A composite group of terrestrial pulmonate mollusks with a partially or completely reduced shell (Fig. 4). On the head, next to the mouth opening, there is a pair of labial tentacles, on top of which are eye tentacles that carry eyes. The narrowed section of the body between the head and the mantle is called the "neck". On the bottom of the neck, a duct of a gland that secretes mucus opens. In addition to this gland, numerous mucous glands are scattered over the entire surface of the body, so the entire body of slugs is covered with mucus. The main purpose of mucus is to moisturize the skin. There is a genital opening on the right side of the neck. The mantle has the appearance of a flat thickening on the dorsal side of the body. Near the right edge of the mantle there is a breathing hole leading to the lung cavity. An anus and an excretory pore open near the respiratory opening along the right edge of the mantle. Slugs are bisexual animals. During mating, male gametes are exchanged. Eggs are laid in moist shaded places.

Most slugs feed on plants, lichens, or fungi. Predatory slugs feed on oligochaetes or other types of molluscs. Active at night, hiding during the day. Slugs that settle in areas occupied by agricultural crops can cause significant damage to plantings of cultivated plants. For example, the field slug (Agrolimax agrestis) eats sown grains and shoots of winter wheat and rye, while the net slug (Deroceras reticulatum) causes great damage to the crop of tomatoes and cabbage.

Description of classes, subclasses and units of the Mollusk type:

• Class Gastropoda (Gastropoda)

  • Subclass Pulmonary (Pulmonata)

Many different snails live in reservoirs, rivers, gardens, but the most common species is the pond snail. It lives in places where there is enough moisture, so it can be seen all over the world. This mollusk is quite often settled in aquariums, as it copes remarkably with the plaque that forms on glass, stones or other objects, and it is also interesting to watch such a snail.

The pond snail copes remarkably with the plaque that forms on the glass of the aquarium.

Description of the mollusk

Prudovik is freshwater snail, which has a well-developed spiral shell. The shell itself consists of five or six turns. On one side, it has a mouth, and on the other, a sharp peak. It reliably protects the soft body of the snail from various adverse effects and mechanical damage.

The pond snail breathes with the help of lungs, and therefore it is forced to periodically rise to the surface of the water. At the very edge of the shell there is a special round hole that just leads to the lung. And it is there that the blood is enriched with oxygen and carbon dioxide is released.

The body of a pond snail consists of three main parts:

• heads;
• torso;
• legs.

The leg of a freshwater inhabitant occupies the abdominal part of the body. It is muscular, with its help the snail moves along the surface. Life cycle in mollusks it is rather short, since in winter they all die. Depending on the species, pond snails differ from each other in the color of the shell, body and legs, and they may also have various shape and shell thickness.

The most common types

Snails are unique animals that do no harm to humans, on the contrary, they are of great benefit, as they actively eat various weeds, clean the aquarium well from build-up and even have healing properties. In nature, there are many variants of the pond snail, each of which has its own characteristics.

But the most common are the following types:

There are other types of these molluscs, but they are much rarer. For example, there are pond snails that live at a depth of up to 250 m or at an altitude of 5 thousand meters.

Nutrition and reproduction

A large pond snail feeds mainly on plant foods. In nature, it eats various weeds, algae and even rotten plants. In an aquarium with long tongue it scrapes off the plaque that forms on the walls. And this mollusk eats any food that settles on the bottom.

As additional feeding, small pieces of eggshell and chalk can be placed in the aquarium. From vegetable food, snails can be given an apple, cabbage, zucchini, pumpkin, carrots, lettuce.

In nature, the pond snail eats various weeds, algae and even rotten plants.

Prudoviki, like many other snails , are hermaphrodites, but their fertilization occurs in a cross way. And they are also able to independently fertilize their own eggs. These lovers of moisture at a time lay a large number of eggs, which are enclosed in a special transparent mucous masonry. Usually it has an elongated shape and is attached to various underwater objects, most often to vegetation. Sometimes in one such clutch there are up to 300 eggs.

The eggs themselves are small and almost transparent. After about a month, they hatch into small snails, which outward signs are indistinguishable from adults. Pond snails reproduce quite actively, therefore, if they are in an aquarium, you need to periodically remove excess masonry. In captivity, these mollusks can live up to two years, and during this period they lay eggs up to 500 times.

Difficulties in maintenance and illness

Prudoviks are completely unpretentious animals, but main difficulty their content is they can carry dangerous diseases which are almost impossible to recognize at first glance. The most common disease in these mollusks is fungal infection. And if an infected individual is placed in a common aquarium with fish and other inhabitants, then it can quickly spread the infection.

To avoid similar situation, before planting a pond snail in a common aquarium, you need to hold it in quarantine for several days. During this period, you should put it daily for several minutes in a weak solution of potassium permanganate or table salt.

If the snail does not consume the right amount of minerals and trace elements, then the walls of its shell may begin to become damaged or thinner. In this case, the pond snail should begin to be fed with foods that contain a high content of calcium. After a while, the shell will overgrow and fully recover.

In gastropods, the body consists of a head, trunk and legs. The leg is a muscular abdominal part of the body, leaning on which the mollusk slowly glides.

Most gastropod molluscs have a spirally twisted shell (which is why they are also called snails), in which the animal can completely hide. At the bottom of the shell is a wide opening - the mouth through which the mollusk protrudes its head and leg when moving. Some terrestrial gastropods - slugs - do not have shells.

In the pharynx, gastropods have a muscular tongue covered with spines - the so-called grater. Using it, the mollusk scrapes plant tissues or scrapes off the plaque formed on underwater objects from various microorganisms.

Key to families

1(4) The mouth of the shell, when the mollusk draws its head and leg into it, is closed by a thin cap attached to the leg.
2(3) On the curls of the shell there are dark longitudinal stripes (may be poorly visible due to the plaque covering the shell), the size is up to 45 mm;
3(2) Shell without dark stripes, one-color; the value is not more than 12 mm;
4(1) There is no lid at the mouth of the shell, so the compressed sole of the foot is visible on the mollusk hiding in it.
5(6) The coils of the shell are twisted in one plane;
6(5) The shell is twisted cone-shaped.
7(8) The shell is twisted to the right (if you take the shell so that the top is directed away from you, and the mouth towards you, then the mouth will be located to the right of the center line);
8(7) The shell is twisted to the left (the mouth is to the left of the center line); FAMILY POND (Lymnaeidae)

In pond snails, the shell is twisted spirally, in several turns, in the form of a turret. About 20 species are found in the USSR.

Common pond snail (Lymnaea stagnalis) The largest of our pond snails, the height of the shell is 45-55 mm, and in some individuals even up to 65 mm. It lives in stagnant water bodies - ponds, lakes, river backwaters with abundant vegetation. Here you can see how the pond snail, sticking its leg and head with tentacles out of the shell, slowly glides over the plants. Having reached the surface of the water, the pond snail spreads its leg wider and slides, hanging from below to the surface film of water. At the same time, at the mouth of the shell, on the side of the leg, a round breathing hole can be seen. In the middle of summer, the pond snail rises to the surface of the water 6-9 times within an hour. Distributed in Europe and North Asia to Kamchatka.

Ear pond snail (Lymnaea auricularia) This mollusk has a shell with a very wide mouth, shell height 25-40 mm, width 20-30 mm. Inhabits the surf zone of stagnant water bodies. Distributed in Europe and Asia (except the southeast).

COIL FAMILY (Plarmrbidae)

In coils, the turns of the shell are located in the same plane. Coils are not as mobile as pond snails, and cannot be suspended from the surface film of water. In the USSR, there are 35 types of coils.

Coil horn (Planorbarius corneus) This mollusk has a shell diameter of up to 35 mm. It lives on plants in stagnant water bodies, in the same place as the common pond snail, but rarely rises to the surface of the water. Distributed in Europe and Western Siberia to the Ob.

Coil bordered (Ptanorbis planorbis) The shell of the bordered coil is dark brown, 20 mm in diameter, with 5-6 whorls. On the last whorl from below there is a sharp protrusion - the keel. It lives in shallow water bodies and in the coastal part of large water bodies. Distributed in Europe and in Western Siberia to the Yenisei.

Coil twisted (Anisus vortex) The shell is yellow, up to 10 mm in diameter, with 6-7 whorls. The last whorl has a sharp, downwardly displaced keel. It lives in coastal thickets of stagnant water bodies, often floats on the surface of the water. Distributed in Europe and in Western Siberia to the Yenisei.

FAMILY PHYSIS (Physidae)

In physids, the shell is in the form of a turret, like in pond snails, but twisted to the left.

Fiza vesicular (Physa fontinalis) The shell is dull, pale yellow, 10-12 mm high, 5-6 mm wide, the height of the mouth is more than half the height of the shell. Lives on vegetation in various permanent reservoirs. Distributed in Europe and North Asia.

Aplexa sleepy (Aptexa hypnorum) The shell is shiny, golden-brown, 10-15 mm high, 5-6 mm wide (the height of the mouth is less than half the height of the shell). Lives only in temporary water bodies that dry up in summer. Distributed in Europe, Western Siberia and the south of the Far East.

FAMILY LUZHANKI (Viviparidae)

The mouth of the shell at rest is closed with a lid. Shells with dark longitudinal stripes. Luzhanok is also called viviparous, since they do not lay eggs, like other mollusks, but give birth to small, already shelled meadowsweet.

Marsh Luzhanka (Viviparus contectus) Sink height up to 43 mm. It lives in lakes, ponds, sometimes even in puddles with clear water. Stays on the bottom. Distributed in Europe and Western Siberia to the Ob.

BITINIA FAMILY (Bithyniidae)

As in meadow meadowsweet, the mouth of the shell is closed with a cap at rest, but the shells are one-colored, without stripes.

Bithynia tentacle (Bithynia tentaculata) Sink height up to 12 mm. It lives in stagnant and weakly flowing water bodies, on stones, in silt and among plants. Distributed in Europe and Western Siberia.

Terrestrial gastropods

Terrestrial gastropods can be divided into two groups: snails, which have a shell, and slugs, which do not have a shell (in some species, a small remnant of the shell is hidden under the skin and is not visible from the outside). Since the skin of mollusks is naked, many species adhere to wet habitats. In addition, animals are usually motionless during the day. At the same time, snails completely hide in the shell, sticking their soles to the substrate, and slugs crawl under shelters - stones, leaves, between lumps of soil. But at night, and in rainy times and during the day, mollusks crawl from place to place.

snails

In land snails, the shell is spirally twisted. In some species, the shell is elongated, so that its height noticeably exceeds its width; in other species, on the contrary, the shell is low and its width is greater than its height. During movement, the mollusk protrudes its head and leg from the shell. There are 4 tentacles directed forward on the head. At the ends of two more long tentacles there are dark balls - these are the eyes. If you gently touch the tentacles, the mollusk immediately draws them in, and if it is strongly disturbed, it will completely hide in the shell. Several hundred species of snails are found in the USSR. Basically, these are very small, difficult to distinguish species from each other (often only by internal structure). We will consider only some of the largest and most widespread forms.

Amber ordinary (Succinea putris) It got its name for the amber-yellow color of the elongated, thin, fragile, almost transparent shell. Shell height 16-22 mm, width 8-11 mm. Shell with 3-4 whorls, last whorl strongly swollen and dilated, ovoid aperture. Amber lives in damp places - in wet meadows, near water bodies, it can often be seen on the floating leaves of aquatic plants, and sometimes it even plunges into water. Widespread throughout the USSR.

Cochlicopa slippery (Cochticopa lubrica) This is a small snail, with a smooth, shiny, elongated, conical shell, 6-7 mm high, 3 mm wide. It is quite common in damp places - in meadows, in grass, in moss, in fallen leaves of damp forests. Distributed throughout the USSR.

Iphigena swollen (Iphigena ventricosa) This snail has an elongated, fusiform, ribbed, reddish-horn shell, 17-18 mm high, 4-4.5 mm wide, with 11-12 whorls. A flat tooth-like protrusion protrudes from above into the mouth. It lives in forests, on the litter, on mossy tree trunks. Distributed in the Baltic States and the middle zone of the European part of the USSR.

Kochlodina rocky (Cochlodina laminata) In this species, the shell is elongated, fusiform, slightly swollen, smooth, shiny, light horn, 15-17 mm high, 4 mm wide, with 10-12 whorls. Two lamellar curved protrusions are visible at the mouth. It lives in forests, on rocks, stumps, tree trunks. Distributed in the middle zone of the European part of the USSR, north to Leningrad region, east to Kazan.

bush snail (Bradybaena fruticum) The shell of this snail is spherical, almost smooth, 16-17 mm high, 18-20 mm wide, with 5-6 whorls. The color varies from grayish-white to reddish-horn, often a narrow brown band is visible on the last whorl of the shell. Lives in shrubs deciduous forests, gardens, often the bush snail can be found on nettles and coltsfoot. Sometimes it climbs quite high on bushes, tree trunks and fences. Distributed in the European part of the USSR, in the Crimea and the North Caucasus.

garden snail (Cepea hortensis) The shell of the garden snail is kubariform, similar to the shell of a shrub snail, 15-16 mm high, 19-21 mm wide, with 4-5 whorls, dark spiral stripes are visible on all whorls. It lives in sparse bushes and forests, on stones and rocks. Distributed in the Baltics

hairy snail (Trichia hispida) In this small snail, the shell is covered with fine hairs (in older individuals, they can be erased). The shell is 5 mm high, 8-9 mm wide, grayish or reddish-brown in color, usually with a light stripe on the last whorl. It lives in bushes, on the ground in forest litter, under stones, deadwood. Distributed in the forest zone of the European part of the USSR, up to the Leningrad and Perm regions. Often causes harm to home gardens, fruit and berry crops and ornamental plants, scraping the tissues of the leaves so that only longitudinal thick veins remain from them.

SLUGS

Slugs have a naked body, devoid of a shell. In a calm state, slugs look like small slimy lumps, but when moving, their body is greatly stretched. Like snails, 4 tentacles directed forward are visible on the head. Two longer tentacles have eyes at the ends. A short neck is visible behind the head, passing into the back. Immediately behind the neck, an oval thickening is visible on the back, as if another layer of skin was superimposed on top. This is the so-called mantle, covering the respiratory organ - the lung. On the right side of the mantle, a rounded breathing hole is visible. As the name suggests, slugs produce a lot of mucus. It primarily protects the mollusks from drying out. In addition, mucus helps them to glide. A crawling slug always leaves a noticeable shiny slimy trail. In the middle zone of the European part of the USSR, 16 species of slugs live. Of these, we will consider the most common, widespread forms.

Key table of genera

1(2) The breathing hole is in front of the right edge of the mantle. When moving, the end of the leg protrudes slightly from under the back;
2(1) The breathing hole is located at the back of the right edge of the mantle. The leg does not protrude from under the back when moving.
3(4) Large slugs, over 100 mm long.
4(3) The size of the slugs does not exceed 50 mm.
5(6) Slime yellow;
6(5) The mucus is colorless, with irritation of the mollusk - milky white; GENUS ARION (Arion)

The body is thick, massive. The mantle is oval, rounded front and back. Breathing hole in front of the right edge of the mantle. When moving, the end of the leg protrudes slightly from under the back.

Arion brown (Arion subfuscus) Body length up to 80 mm. The mantle is about 1/3 of the body length. Coloring can be different, from brown to orange, more often rusty. The middle of the back is usually darker. Lives in deciduous, mixed and coniferous forests, occasionally found in old parks and cemeteries. A favorite food is cap mushrooms, in which the slug eats away large cavities. It can also feed on dead plant parts and animal carcasses. Distributed in the forest and forest-steppe zone of the European part of the USSR. in the Altai Territory, Eastern Siberia, the Amur basin and the Primorsky Territory, the subspecies Arion brown Siberian (Arion subfuscus sib ire us), which is distinguished by a monochrome black color of the body, lives. In warm, damp summers, this slug causes damage to vegetable gardens and fields located next to the forest.

Arion striped (Arion fasciatus) Body length up to 50 mm. The mantle occupies about 1/3 of the body length. The coloration is light - cream or yellowish-ash, the middle of the back and mantle is slightly darker. There are clearly defined dark stripes on the sides. It occurs more often in cultivated biotopes - vegetable gardens, fields, gardens, parks. Often causes significant damage to crops. Distributed in the northwestern and central regions of the European part of the USSR.

GENUS DEROCERAS (Deroceras)

Small slugs, quite slender and mobile. The skin is almost smooth, with weak grooves, without coarse wrinkles. Breathing hole in the back of the right edge of the mantle. The mucus is colorless, when the mollusk is irritated it is milky white.

slug reticulated (Deroceras reticulatum) Body length 25-35 mm. The mantle occupies about half the length of the body. The coloration is mostly cream or light coffee, with dark spots forming a grid-like pattern, especially noticeable on the mantle and back. The head and neck are also covered with small spots; tentacles are blackish. Dwells on open places, avoiding forests and shrubs, more often on clay soils - meadows, fields, vegetable gardens, landfills, and in cities - in parks and gardens. Of all the slugs, the most dangerous pest crops. In gardens, it willingly attacks cabbage, eating out large holes not only in the outer leaves, but also inside the head. In rainy years it damages winter seedlings. Widely distributed in the European part of the USSR.

field slug (Deroceras agreste) Body length 35-40 mm. The mantle occupies about 1/3 of the body length. Coloring from almost white to cream, without a dark pattern. It lives in open places - meadows, swamps, near roadside ditches, on forest edges, but, unlike the reticulated slug, avoids places with cultivated soil. Widely distributed throughout the USSR.

Slug smooth (Deroceras laeve) Body length up to 25 mm. The mantle occupies about half the length of the body. Coloring from reddish-brown to almost black, one-color. Very moisture-loving and cold-resistant. It lives in swamps, wet meadows, damp forests, on the banks of small overgrown reservoirs - here it can be found not only on soil and plants, but also on their underwater parts. Widely distributed throughout the USSR.

GENUS LIMAX (Limax)

Large slugs, more than 100 mm long. The coloration is spotted, sometimes the spots merge into dark stripes. A keel protrudes on the caudal part of the back. The body is wrinkled, the wrinkles are long, convex, with deep grooves between them.

Slug black (Limax cinereoniger) Body length 150-200 mm. The mantle occupies about 1/4 of the body length. The coloration is black or dark gray, the keel is light. Tentacles with black dots. Lives in deciduous and mixed forests, can also live in coniferous forests with good grass cover. It feeds mainly on fungi and lichens. Distributed in the Karelian Autonomous Soviet Socialist Republic, the Baltic States, Belarus, in the western and central regions of the RSFSR, east to Nizhny Novgorod.

Slug big (Limax maximus) Body length up to 130 mm. The mantle occupies about 1/3 of the body length. The coloration is variegated: on a yellowish, ash-gray or off-white background, 2-3 pairs of dark stripes or rows of dark spots. The tentacles are one-colored, without dark dots. It lives in cities - in parks, gardens, greenhouses, vegetable stores, where it can harm. Distributed in the northwestern and central regions of the European part of the USSR.

GENUS MALAKOLIMAX (Malacotimax)

Malacolimax gentle (Matacolimax tenellus) Body length up to 50 mm. The mantle occupies about 1/3 of the body length. The color is monochromatic, often yellow, greenish or grayish-yellow, sometimes orange-yellow. The head and tentacles are black or dark brown. The slime is yellow. It lives in deciduous forests, occasionally in coniferous ones. Eats hat mushrooms and lichens. Distributed in the northwestern, western and central regions of the European part of the USSR.

CLASS Bivalve mollusks (Bivalvia)

In bivalve mollusks, the shell consists of two halves connected on the dorsal side by an elastic ligament. On the ventral side, the halves of the shell can move slightly apart, and the leg of the mollusk protrudes through the gap formed. When moving, the mollusk pushes the silt or sand at the bottom with its foot, like a plow, catches the ground with its foot and pulls the body with the shell forward, again pushes the leg forward, pulls itself up again and thus crawls along the bottom with small steps. Some bivalves do not move, but sit in one place, attached to the substrate with special sticky threads. Bivalve molluscs do not have a head, so there is no grater. They feed on small planktonic organisms, which are sucked together with water through a siphon hole located at the rear end of the body. All bivalves live in water.

FAMILY PERLOVITSA (Unionidae)

The shells of barley have an elongated oval shell. On each leaf, the most convex, prominent part is visible - the top. Concentrating around the top, arcuate lines pass on each leaf. Some of these arcs are sharper, darker - these are annual arcs, they can be used to approximately determine the age of the mollusk. There are 4 genera in the family. The most famous are barley and toothless.

GENUS OF PERLOVITSA (Unio) Barley shells have a thick-walled shell, the tops of the valves protrude upwards. If you look at the shell from the end, then the place of fastening of the valves - the ligament - will be in the recess.

Barley ordinary (Unio pktorum) The shell of the common barley is long, narrow, up to 145 mm, with almost parallel dorsal and ventral margins. The color in young individuals is yellow-green, in old ones it is greenish-brown. It lives in lakes and rivers, in places with a slow current, on sandy, not very silted ground. Distributed in the European part of the USSR, except for the north and northeast.

Barley swollen (Unio tumidus) This species has a shorter shell, up to 110 mm, with non-parallel edges. The habitats and distribution are the same as those of the common barley.

GENUS OF TOothless (Anadonta) In toothless, the shell is thin-walled, the tops of the valves do not protrude much. If you look at the sink from the end, then the place of fastening of the valves is not deepened. Some species have a large keel on the upper edge of the valve. The shape of the shell is very variable in individuals of the same species living in different water bodies.

GENUS PEA (Pisidium) In peas, the top of the shell valves is shifted to the side, the shell is short-oval. The size of the peas does not exceed 11 mm.

River pea (Pisidium amnicum) The shell diameter of the river pea is 10-11 mm. It lives in the backwaters of rivers and lakes, on silty-sandy soil. Distributed in the European part of the USSR and in Siberia to the Lena.

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

Structure

The body of the pond snail (Fig. 58) is enclosed in a shell spirally twisted in 4-5 turns, which has a sharp top and a large opening - the mouth. The shell of wine 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.

In the body of a pond snail, three main parts can be distinguished: the torso, 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. Molluskshaving legs like those of a pond snail are called gastropods.

The sole of the foot secretes mucus, with the help of which the foot slides over underwater objects or even over the surface film of water, hanging from below, the pond snail moves smoothly forward.

The body repeats the shape of the shell, closely adjacent to it. In the front part of the body is covered by a special fold - the mantle. The mantle (skin fold) 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 passes into the head. A mouth is placed on the underside of the head, and two sensitive tentacles are placed on its sides. When touched, the pond snail quickly draws its head and leg into the shell. Near the bases of the tentacles is on the eye.

Digestive system

The common pond snail is a herbivore. The mouth leads to the throat. A muscular tongue covered with teeth is placed in it - this is the so-called grater. With it, the pond snail scrapes off plaque from organic matterformed on underwater objects, or scrapes the soft parts of plants. In the pharynx, food is processed by the secretions of the 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 an anus located above the head.

Respiratory system

Although the pond snail lives in water, it breathes atmospheric air. For breathing, 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-chamber heart, consisting of an atrium and a ventricle, and blood vessels.

Arterial blood enters from the lung into the atrium, then into the ventricle, and from it moves through the vessels to all organs of the body and pours out between them. Such a circulatory system is called open. Giving oxygen and getting rich carbon dioxide, the blood is collected in the venous blood vessels and enters the lung, where gas exchange again takes place. Oxygenated blood travels 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 the movement of blood slows down in the spaces between the organs. 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 breaks off near the anus.

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

Nervous system

The nervous system of the pond snail is of the nodal type and includes a near-pharyngeal 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 bubbles lying on the surface of the nerve node of the legs. In these bubbles in a liquid medium 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 the copulation of two individuals, mutual fertilization takes place, that is, the exchange of male gametes - spermatozoa. After that, the individuals disperse and lay fertilized eggs tied into gelatinous cords. They attach themselves to underwater plants.

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

Position in systematics (classification)

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

On this page, material on the topics:

• Message about the pond snail briefly

• Does the common pond snail secrete mucus

• Type of circulatory system in a pond snail

• Adaptation of mollusks to the habitat common pond snail

• Grater at the pond

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