Do Snails Grow Their Shells?

Snails are very interesting creatures. Have you ever wondered if they are born with their shells and if their shells then grown with them? Here, we will take a look at that very question, plus some more interesting related questions.

Do snails grow their shells?

Snails are born with their shells, and then as the snail grows, their shell grows with them! Female snails lay eggs in a small white clump right under the surface of the soil. In only a couple of weeks, these eggs hatch, and the baby snails already have their shells attached! The shells of these little snails are very soft and delicate, and they also lack in color.

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The baby snail then eats the egg that it hatched from. This gives them some much-needed calcium. This calcium helps the shell to harden. Some snails will also eat the shells of unhatched siblings, giving them another source of calcium.

Over the next three months or so, the shells will get thicker and get the coloration that is associated with this creature. And then, as the snail continues to grow, the shell will grow right alongside it!

The snail’s body is called the mantle. The mantle produces more of the softshell material that they were born with. This then goes to the edge of the shell (this is then called the “lip” of the shell). The lip will then harden after some time, and then more soft material will be added to the shell.

Giant African Snail
Giant African Snail

As the snail gets bigger, and its shell grows, the number of spirals in the shell will increase as well! (Fun fact: You can tell how old a snail is by counting the shell rings! Most snails live about six to eight years, but in captivity, it has been reported that snails can live to be up twenty-five years old!)

Since snails grow their shells for their entire lives, they need to eat a lot of calcium to make their shell hard and strong. They get the calcium that they need by eating soil or munching on limestone. Snails that live on land will also eat vegetables in gardens if it is available to them (such as broccoli, turnip, and spinach)- this is what gives them the reputation as a garden pest.

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In a way, a snail’s shell is a bit like our fingernails- they keep growing. If a snail were to get a little bit of a crack in its shell, it would be able to repair it. But, sadly, if the snail’s shell becomes significantly damaged, the snail will not grow a new shell fast enough, and the snail will die. This is because the shell plays such an important role in keeping the snail safe.

The shell of a snail is an external skeleton (which is also known as an “exoskeleton”). This shell protects the snail from predators, from the sun, and from drying out.

Because of this, snails cannot “outgrow” or leave their shells behind. This goes back to the example with our fingernails- snails can no easier leave their shells behind than you can leave your fingernails behind!

Snail Shell
Snail Shell

Most snail shells spiral in a clockwise direction (scientists estimate that about 90% of all of the world’s snails have shells that turn to the right).But then some snails have shells that turn in a counterclockwise direction. This is caused by natural influences or genetics. These shells are called “sinistral shells.”

But even though the shell can grow in either direction, scientists do not believe there is any biological reason that this happens (it is random, just like how some people are righties and some people are lefties).

Do all shelled animals grow their shells?

Since snails grow their shells, you might be wondering about other shelled animals, such as turtles, hermit crabs, armadillos, and clams.

Some of these shelled animals are born with their shells, while others are not. Turtles and tortoises are just like snails in that they grow their shells! Their shells are always the perfect size for the turtle and this is because their exoskeleton (the shell is made from the turtle’s spine and rib cage) grows with them (in the same way that your vertebrates grow with you).

But the way that their shells grow is a little different than the way a snail shell grows. Turtles have “scutes” on their shell that peel or shed, which simply make way for newer and bigger scutes.

Armadillos are also born with their shell. The shell of an armadillo is called a “carapace” and it is already developed when baby armadillos (called pups) are born. This shell is softer than an adult’s carapace, and it will harden as they get older. Interestingly enough, armadillos are the only living mammals to have shells on their bodies!

RELATED: Do Armadillos Lay Eggs?

Hermit crabs, on the other hand, do not grow their own shells. Instead, they just borrow shells! Hermit crabs have soft bodies and they steal shells from other animals in order to keep themselves safe. Most of the time, they take abandoned sea snail shells- then they just tuck themselves inside of it and carry it with them everywhere they go! Then, when they get too big for that shell, they discard it and get a new, bigger discarded shell somewhere else!

Like hermit crabs, clams are not born with a shell! Clams are just little swimming larvae when they hatch. They will attach themselves to grains of sand or even become parasites on fish gills. Then, as they get a bit older, clams will go through a process called “metamorphosis.”

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They will settle on the ocean floor. Then, they will begin to grow their shell. Like snails, clams grow their shell from the mantle part of their body. The shell is made out of protein and minerals. Then the shells will grow from the bottom up (and from the inside out) to form what you picture as a clam.

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