how do snails grow their shells?

Answer 1

Yes, they do grow it. It is secreted from an area of the skin called the mantle.

Answer 2

When a snail grows, the shell has to be enlarged to fit the snail's body. To accomplish that, a snail gradually extents its shell by adding new parts at the shell opening.
The growth process is carried out in two stages: In the first stage the thin, transparant and organic outer layer (periostracum) is created, on which the calcified inner layers are deposited in the second stage. The shell material is secreted by specialized cells of the mantle.
Apple snails can grow their shell very fast under the right conditions: peak rates of 0.5 cm (0.2 inch) new shell a day do occur.
The computer animation above illustrated the growth of a shell. The oldest part of the shell is located at the top, while the most recent part is located near the shell opening (aperture).
When a new shell part is added, small vertical lines (transverse stria) are formed on the surface of the shell.
The thickness and regularity of those lines varies with the environmental conditions, the age of the snail and the species. They provide information about the environmental conditions during the snail's life (similar to what the grains of wood tell us about the life of a tree).
The operculum or trapdoor of apple snails grows in a similar way as the shell: a new material is added in a circular fashion. The result is a concentric operculum with the oldest part in the center. The operculum is only enforced with a calcium layer in the genus Pila, the other genera have a horny operculum.
Due to the way snails solve the growth problem (enlarging their shell), they always have to carry the whole construction with them, even if they do not inhabit the oldest whorls. Crustaceans and insects, for example, use another option to overcome the growth problem: they regulary shed their whole skin when they grow and replace it with a larger one. The advantage of that method above the snail-grow method is that they do not have to carry around obsolete body parts. On the other hand, a crustacean or an insect is a very vulnerable when it has shed its old skin and the new skin still has to harden.

Answer 3

you are all wrong.
Snails were actually invented by the Nazis. They knew that nearly all people in England had front or back gardens and decided that this was the best way to invade. They took slugs and housed little radio receivers on them and little parachutes. The blitz was a cover to really drop these 'panzer-sluggen' into peoples back gardens. When it rained they would come out of the hedges and onto the pavement where they would get better reception for their orders to be radio'd. However these slugs realised that they were in danger of being trodden on aned stayed in the heges. Hitler went mental.

Answer 4

they start off like slugs and stuff and then a little horn thing grows on its back and then it grows bigger and bigger until its a shell!!
tada
check www.wikipedia for an article about snails

Answer 5

It is an excretion that builds and builds on itself as the snail gets bigger.

Answer 6

tempo needs help