How is a snail born?

Answer

Dear James,

Most snails lay eggs from which baby snails hatch (kind of like a chick hatching from a bird’s egg). Those baby snails already have a house at that moment!
Now there are also snails that keep their eggs in a kind of brood bag and that incubate their eggs, as it were, internally. When the baby snails hatch, they stay in that brood bag for a short time and only when they are slightly bigger do the baby snails come out from the brood bag of the mother snail. Such snails that do not lay eggs, but that give birth to their baby snails directly, are called viviparous. Of course, those baby snails already have their home.
Some sea snails do it differently: they produce eggs that they float around in the water among the plankton (these are all those microscopic animals and plants that float around in water). A very small larvae that does not have a house and that actually does not look like a snail at all then crawls out of those planktonic eggs. That larva is called the Trochophora larva and it floats among the plankton, where it will feed and grow. When the larva is big enough (but for us it still remains microscopic) it will undergo a metamorphosis which creates a new type of larva that is called the Veliger larva. The Veliger larva now has a house and as this larva grows, the house becomes heavier and the larva sinks to the bottom, where it will develop further into an adult snail.

In the video, for example, you see a baby snail of an apple snail that is still in the egg. The baby snail moves in the egg and if you look closely you will see the eyes (two dark dots). You can also clearly see the house.

I also add some photos and videos here that give you a better idea of ​​the birth of snails.

Hopefully this answers your question.

Kind regards,
Thierry Backeljau