From the childhood we know that snails are the creatures that bring their house on the back. However, no one knows the real value of the shell. This fact is very interesting, because the shells of different snails differ by shape, structure and color.
Like other mollusks, the shell of the snail is an external skeleton. Therefore, it helps snails to move and holds parts of their body. The structure consists of the three layers:
- Periostracum. The outer layer, which consists of conhiolin, a special protein. It is organic.
- Ostracum. Middle layer. Lime.
- Hypostracum. The inner layer is a mother-of-pearl shade. Not all types of mollusks have it. Lime.
The mantle, the skin fold that holds the body together with the shell, is not considered part of the shell, but performs an important function. In addition, the internal organs and muscles of the snail are also attached to the inner side of the shell.
The shell can be:
- round or conical;
- Smooth or textured.
The exterior of the shell determines the type of mollusk. However, there is a common characteristic: the spirals are twisted clockwise, with rare exceptions. Thus, for example, the famous grape snail Jeremy has the mirrored internal organs, so the spirals on its shell are twisted in the opposite direction.
Important! Young snails hatch with a shell, which is very soft and translucent. As they grow older, they absorb limestone from the water. The substance is deposited in a circle and forms spirals. Thus, the age of the individual can be determined by the number of spirals on the external skeleton.
The ribbed surface of the shell retains moisture and also increases the strength of the external skeleton. It can be observed in grape snails (Helix Pomatia).
They can be
The stripes can be:
- zigzag or diagonal.
Edible snails, used for the preparation of escargot, have brown color (it can vary from the light amber to dark brown). The popular small and big snails have grey shells correspondingly.
Important! Decorative species of snails can have brightly colored shells. Moreover, the brighter the color, the more dangerous the creature is. Such mollusks are usually poisonous, so they are not edible.
Snails without shell
Shellfish without an external skeleton have scientific name “slugs”. Scientists believe that the shell of such creatures has atrophied during evolution: due to the spread of slugs in places with high humidity, but the lack of calcium, necessary for a strong shell.
The snails that were originally born with a shell cannot live without their “house”. Besides the fact that they are in danger from predators, they will not be able to move and will quickly lose moisture. But if the external skeleton cracked a little or a piece of it is broken, the snails can still be saved.