When you first see a tortoise it’s easy to understand why you would believe that they can get out of their shells, as there doesn’t seem to be anything that would prevent them from leaving their shell. But is that true?
Turtles can not live without their shells. The shell of a turtle is fused with the rest of its body, and it’s an important part of its skeleton.
So we probably won’t see any turtle without a shell too soon, if ever. But this doesn’t mean that turtles without shells didn’t exist, over the ages, there have been quite a few turtles that didn’t have a proper shell. But before we take a look at those turtles, let’s start by seeing what turtle shells really are.
What Are Turtle Shells?
Turtle shells have been called a lot of things: a defense mechanism, an exoskeleton, an armor, the home of the turtle, etc. But what a turtle shell really is, is part of the skeleton of a turtle.
Here is a picture of the skeleton of a turtle, so you can get a better understanding.
Photo by Pere López on Wikipedia
At first, it might seem that the shell is just one big solid piece of bone, but in reality, it’s actually made out of multiple smaller bones that have fused together.
While there are 60 different bones in the shell, it is usually divided into 3 distinct parts. The carapace, (the upper part), the plastron, (the lower part), and the bridge (the part that keeps them together)
Here are two pictures so you can get a better idea.
Photos by braindamaged217 on Flickr
Photo by braindamaged217 on Flickr
Why Turtles Can’t Live Without a Shell
Since the shell is a big part of the skeleton of a turtle it’s safe to say that turtles can’t live without it. This is because, unlike most other animals that have skeletons, the turtle’s skeleton is almost entirely fused together, and you can’t remove parts of it.
Over the years scientists have studied more than 300 different turtle species, and no matter how different the shells were in shape, none of them could be removed.
This means that not even turtles themselves are able to remove the shell. But why would they want to do that in the first place, after all, it has so many advantages.
The Purpose of the Shell
The simplest answer is that shells are there to protect turtles, but this answer doesn’t tell the whole story. While protection is one of the main purposes of the shell there are a few more things that shells do.
One of the most important things is that it helps aquatic and sea turtles reach higher speeds underwater due to its aerodynamic shape. And it helps with buoyancy – the ability to move up and down in the water.
Turtles are great diggers, and their shell allows them to breathe better underground. If while digging a tunnel earth fell on an animal, his lungs wouldn’t be able to properly expand to breathe air, but for turtles, this is not a problem since their lungs are protected by the shell.
Turtle shells also provide a lot of stability which can be extremely useful for a turtle and a tortoise when it’s digging.
Turtles reproduce through eggs, as most reptiles do. But unlike most reptiles that are extremely vulnerable while they carry eggs, female turtles don’t have to worry about their safety, or the safety of the eggs during this time since the shell helps protect the eggs.
There are a few more things that shells do, but there are even a lot more things that shells did but no longer do. As you can imagine the bones of a turtle haven’t fused together overnight, it took millions of years, and it happened in stages. And every stage took happened due to a certain need.
How Turtles Got Their Shells
The first know ancestors of the turtles lived exclusively on land, to be a little more precise they actually spent more time underground than on the ground. This ancient turtle didn’t have a shell at all, but it did have wide flat ribs, which provided a lot of benefits when it was digging underground.
The next known ancestor of the turtle lived in water, but just like modern turtles it still needed to breathe air, so it stayed closer to the surface of the water This means that it was vulnerable to attacks from below, and the already wide and flat ribs have started fusing together forming the plastron (the lower part of the shell).
Then ancient turtles started moving between land and water more often, but there was one problem, while the plastron offered great protection from attacks that were coming from below, it also slowed them down a lot. So they started developing another layer of protection the carapace (the upper part of the shell).
This is the very short version of how turtles got their shells. If you want to know a few more details I would recommend you to take a look at those two videos on Youtube:
How Do Turtle Shells Grow?
Turtles are born with their shells. While they are in the egg, the shell develops at the same time as the turtles do.
As turtles grow bigger and older, their shell grows at the same time they do. The only part of the shell that doesn’t grow with the turtle are the scutes.
The scutes are a protection layer that protects the shell from harm. The scutes form a relatively thin protective layer around the shell, and they look like this.
The scutes are made out of keratin, the same thing that our nails are made out of. But unlike our nails, they can’t grow enough to keep up with the growth of the turtle, so from time to time they will fall off.
If you want to know more about the role of the scutes and the many ways in which they protect the turtle, and for that other reasons they can fall off, you can check out this article: Do Turtles Shed? (Complete Guide with Pictures)
But why do the shells need protection of their own? Isn’t that one of the main roles of the shell, to protect the turtle? Yes, the shell is there to protect the turtle, but while the shell is an amazing defense system, it has one major flaw. It can’t heal itself.
Can the Shell Heal Itself?
Turtle shells can heal themselves, but only up to a certain extinct. If there is a severe crack, the shell won’t be able to recover completely, and will always have a sensitive spot.
So to prevent this from happening turtles have developed scutes, which will absorb some of the damage, thus protecting the shell.
Turtles could easily heal small superficial scratches, but healing those scratches takes time, energy, and resources, which the turtle could put to better use for things like growing or searching for food.
If a turtle shell had to heal out every small scratch that comes with daily activities, it won’t have enough energy to do other vital things. So to prevent this from happening, they’ve developed scutes, which protect the shell from the daily tear and wear, and when they are damaged they will fall off and another one will take its place.
Related Questions
Can tortoises and turtles survive a broken shell? Yes, turtles can survive with a broken shell, but a broken shell can’t heal itself so the turtle will remain much more vulnerable.
Do turtles feel pain in their shell? Yes, turtle shells are connected to nerves, and they are able to feel pain, or when you touch them. While the shell is not as sensitive as the skin of the turtle, it’s still able to feel.
What are turtle shells made of? Turtle shells are made out of bones, and the exterior is covered with a keratin layer.
How many bones does a turtle shell have? A turtle shell has around 60 bones. It’s really hard to see the difference between them since they are fused together, but biologists have determined that there are about60 bones.
Do turtle’s shells heal? Turtle shells can heal minor injuries, but if the shell is completely cracked, the turtle will not be able to heal its shell.
Can turtles recognize their owners? Turtles can recognize you and they will understand that you play an important part in their lives, but they will not feel any familiarity with you like dogs or cats would. Overall turtles recognize their owners but not in a way you would expect. You can always read more about this in my article: Can Turtles Recognize Their Owners?
Can turtles change their shells? No, turtles are born with their shell and can’t change it over time, as it’s part of their body. In the case of some turtles, the shell will change its appearance over time, some of them will develop spikes, some of them will change their color, and some of them will even change their shape, but it’s still the same shell.
Can you touch a turtle’s shell? Turtle shells are safe to touch, but some turtles can be more aggressive than others, and they might think that you want to attack them, so they might try to bite you when you do so. And there is a good chance that the turtle might be carrying bacteria on their shell so you should always wash your hands after you touch a turtle.
How long can a turtle stay underwater? It depends on the turtle, most sea turtles will be able to go for at least 5 hours without breathing, most aquatic turtles should be able to stay underwater for at least 20-30 minutes, land turtles on the other hand are not very good at staying underwater so 1 minute is the average you can expect them to be able to stay underwater. Here is a list of average times a turtle can spend underwater:
- Box turtle – 1 – 2 minutes
- Desert tortoise – 1 – 2 minutes
- Snapping turtle – 20 – 30 minutes
- Red-eared slider – 20 – 30 minutes
- Map turtle – 20 – 30 minutes
- Green sea turtle – 7 – 10 hours
- Leatherback sea turtle – 7 – 10 hours
- Kemp’s ridley – 7 – 10 hours
- Olive ridley – 7 – 10 hours
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