How Do Snails Get Their Shells?
Snails usually begin to grow their protective shells before they hatch. The common garden snail hatches from a tiny round egg. Hidden under the young snail’s shell is a flap of skin called the mantle. The mantle oozes a limy liquid that quickly hardens into a shell.
As the snail grows in size, it adds coil after coil to its shell, building from the open end (or mouth) as fast as it needs more room. The food that is eaten by the snail provides the materials that form the shell. Without its shell, a snail would have little protection against drying up.
Snail shells come in many different shapes and sizes. Most snails have spiraled shells. Some sea snails have shells that coil into cones. Other snails even have shells that are shaped like macaroni.
A snail’s shell forms a logarithmic spiral. Most snail shells are right-handed or dextral in coiling, meaning that if the shell is held with the tip, or the juvenile whorls pointing towards the observer, the spiral proceeds in a clockwise direction from the tip, or the juvenile whorls to the opening.