In Russia and Europe, there are different types of ponds. Among them, the largest is an ordinary pond, whose shell can reach 7 centimeters. All species breathe easy, therefore, from time to time they are forced to swim to the surface. It is often possible to observe how a snail pond, the photo of which is presented in this article, smoothly and slowly glides along the bottom of the surface film of water, collecting oxygen from the air.
If the mollusks “suspended” in this way are somehow disturbed, then they immediately release an air bubble from the breathing hole and fall to the bottom with a stone. The eared pond is the closest relative of the common. Its shell reaches 2.5 centimeters, which depends on the abundance of feed and temperature in its pond.
The common pond and other species of its family (except for the above, in our reservoirs you can find ovoid, small and swamp) are very variable. In this case, the shapes, sizes, thickness of the shell, the coloring of the trunk and legs of the snails vary. Along with those that have a strong shell, there are species with a very fragile, thin shell that breaks even with the lightest pressure. There may also be various forms of curl and mouth. The color of the body and legs varies from sandy yellow to blue-black.
Structure
The body of the mollusk is enclosed in a spirally twisted shell, which has a mouth (large opening) and a sharp apex. The shell of an ordinary pond is covered with a layer of lime of a horn-like greenish-brown substance. She is a reliable defense of his soft body.
In the body of the cochlea, 3 main parts can be distinguished: the leg, the head and the body - although there are no sharp boundaries between them. Only the front of the body, leg and head can protrude from the shell through the mouth. The leg is very muscular. She occupies the abdominal part of the body. Such snails are called gastropods. At the same time, gliding over the objects with the sole of the foot or hanging from the bottom film of water, the mollusk smoothly moves forward.
The body at the same time copies the shape of the shell, adhering to it very closely. It is in front of it covered by a mantle (special fold). The space between it and the body is called the mantle cavity. The torso in front passes into the head, with the mouth on the underside, and two sensitive tentacles on the sides. Pondovik with a light touch of them instantly draws his leg and head into the sink. Near the bases of the tentacles is located in one eye.
Circulation
The common pond is quite interesting. So, he has a heart, which the blood pushes into the blood vessels. In this case, large vessels are divided into small ones. And of these, blood already flows into the gaps between the organs. A similar system was called "open". Interestingly, the blood washes each of the organs. Then it again gathers in the vessels that lead to the lung, after which it enters directly into the heart. In such a system, it is much more difficult to ensure the movement of blood than in a closed one, since it slows down between organs.
Breath
Despite the fact that the snail lives in water, it breathes atmospheric air. For this, the common pond, the structure of which is described in this article, floats to the surface of the reservoir and at the edge of the shell opens a breathing round hole. It leads into the lung - a special pocket of the mantle. The walls of the lung are densely braided by blood vessels. At this point, carbon dioxide is released and the blood is enriched with oxygen.
Nervous system
This mollusk has a near-pharyngeal concentration of nerve nodes. From them the nerves depart to all organs.
Nutrition
The snail's mouth leads to the pharynx. There is a clove-covered muscular tongue ─ the so-called grater. An ordinary pond, a photo of which can be seen in this article, it scrapes the plaque from all kinds of microorganisms that are formed on various underwater objects, as well as rubs various parts of plants. Food from the pharynx is sent to the stomach, and then to the intestines. The liver also contributes to its digestion. The intestine at the same time opens with an anus in the mantle cavity.
Movements
If the caught pond is put in a jar, it immediately begins to actively crawl along its walls. At the same time, a wide leg extends from the opening of the shell, which serves to crawl, as well as a head with two long tentacles. By sticking the sole of the foot to various objects, the snail glides forward. In this case, gliding is achieved by wave-like, smooth contractions of the muscles, which can be easily observed through the glass of the vessel. It is interesting that the common pond can wander along the lower surface of the water, as we already mentioned above. At the same time, he leaves a thin tape of mucus. It stretches across the surface of the water. It is believed that snails moving in this way use the surface tension of the liquid, being suspended from below from an elastic film that forms on the surface due to this tension.
Such a crawl can be easily observed on the calm surface of the reservoir, going on an excursion or relaxing in nature.
If the mollusk pond, crawling in this way, under slight pressure again plunges into the water, you will see how it again, like a cork, rises to the surface. This phenomenon is easily explained: there is air inside the respiratory cavity. It supports the snail like a swimming bladder. Prudovik can compress his respiratory cavity arbitrarily. In this case, the mollusk becomes heavier, therefore, sinks to the very bottom. But when the cavity expands, it floats to the surface in a vertical line without any kind of push.
Try pond, floating on the surface of the reservoir, immerse in water and its soft body to disturb the touch of tweezers or sticks. The leg immediately retracts back into the sink, and air bubbles stand out through the breathing hole. Further, the mollusk will fall to the bottom and will not be able to independently rise to the surface in some other way, besides climbing onto plants, due to the loss of an air float.
Breeding
The mollusk prudovik is a hermaphrodite, although he has cross fertilization. The snail lays eggs, which are enclosed in transparent mucous cords attached to algae. From the eggs appear small ponds with a very thin shell.
Pond content
Some aquarists allow the keeping of ponds in one common vessel, not realizing that this is often simply unacceptable. Indeed, if, say, ampullaria is grown mainly in artificial conditions (in an aquarium), the snail is placed there directly from a pond, a small lake or a standing reservoir. Pond boats that were caught under natural conditions are more likely to be a source of infectious diseases and fish parasites. Very often, young aquarists are offered to purchase mollusks in the bird market and in various pet stores.
If you still decided to start an ordinary pond, then you need to understand that a temperature of about 22 ° C and its moderate hardness are considered a prerequisite for its maintenance.