A large pond snail is a typical representative of freshwater gastropods. In our article we will consider the habitat conditions and typical structural features of this animal.
Shellfish: features of the organization
В переводе с латинского название этого типа animals means "soft". Some of them have shells. But in any case, the body of these invertebrates is soft and non-segmented. You can meet them in fresh and salt water. So, toothless and perlovits live in ponds and lakes, and mussels and octopuses - in the seas. Snails and slugs can be found on wet land areas.
In the body of mollusks can be divided into three parts:head, torso and leg. Most of them move quite slowly, because the muscles are represented by individual beams. All mollusks have a trunk surrounded by a fold of skin, which is called the mantle.
Basics of classification
Depending on the features of the structure are distinguishedthree classes of mollusks. A characteristic feature of cephalopods is the modification of the legs into tentacles. They are located around the mouth. The tentacles are suckers, with which the animals catch and keep prey. Cephalopods are capable of reactive movement due to a special tubular formation, the funnel. Representatives of this class are squid, cuttlefish and octopus.
Bivalves are perlovi,Zebra mussels, mussels and oysters. All of them have a body consisting of the trunk and legs, as well as a shell of two wings. Large prudovik - representative of gastropod mollusks. Let us dwell on its structure in more detail.
Large prudovik - representative of gastropod mollusks
A large, or ordinary pondfish is found infresh waters rich in vegetation. His body, like all gastropods, consists of the head, torso and legs. The middle part is completely located inside a helically swirling shell, consisting of lime, covered with a layer of horn-like substance. This is a kind of shelter and shelter. The shell of a large pond snail is spirally twisted. Maximum have 4-5 turns. It has a hole called the mouth. The head and leg are pulled in through it. The shell of a large pond snail and horn coil in case of danger is closed with a special lid. This structure is an additional defense against enemies.
The structure of a large prudovik
Почему моллюски, которых представляет прудовик, called gastropods? It's all about the structure of their body. There are no clear boundaries between its parts. The leg is a flat and muscular protrusion, completely occupying the abdominal part of the body. Its surface exudes mucus, which provides easy gliding on various substrates and water film.
On the head of a large pond snail is a pairtentacles. These are the organs of touch. If you touch them, the clam will draw the head inside the sink. At the base of the tentacles are the eyes. Prudoviki also have organs of balance. They are represented by small bubbles, inside which are special little bodies. Changing the position of these structures maintains the equilibrium of the mollusk.
Circulatory and respiratory systems
Big prudovik has a circulatory systemopen type. It consists of a two-chamber heart and vascular system. The blood mixes with the cavity fluid, washing all tissues and organs. From the heart, it enters the arteries, and in the opposite direction it moves through the veins. Despite the fact that the large prudovik lives in water, it breathes exclusively with atmospheric oxygen. To do this, the animal moves to the surface of the water and opens to the outside a breathing hole located at the edge of the sink. It leads to the lung, in which the blood enriches with oxygen.
Digestive and excretory systems
The big pond snail moves slowly but surely.Why does he constantly "travel"? The clam moves in search of food, scraping it from underwater objects with the help of a jaw and a grater. The latter is a few rows of horny teeth. The process of splitting nutrients is accelerated by the enzymes of the digestive glands - salivary and liver.
Over the head pond snail opens anus. And next to it opens the duct of the urinary system. The latter is represented by a single kidney and ureter with a hole.
Reproduction and development
By type of reproductive system, a large pond snail ishermaphrodite. This means that both female and male sex cells are formed in his body. Fertilization of these mollusks is internal. As a result, it is the exchange of sperm. Mollusks place zygotes in gelatinous cords, which are attached to underwater objects. As a result, young individuals with a thin shell develop.
So summarize:a large pond snail is representative of gastropods. These are typical inhabitants of freshwater bodies. Prudoviki have three parts of the body: the head, torso and leg, as well as a spiral swirling shell.
