A tortoise’s shell is one of their biggest and most well-known features. Without them, tortoises probably would not be as popular as they are with most tortoise keepers. Not only do these shells look pretty, but they also play an essential role at keeping your tortoise healthy. From protecting them against predators, to helping them regulate their temperature, to maintaining their overall posture. Having a healthy shell, therefore, is what all tortoise keepers should be striving for.
Proper husbandry is the key here, including maintaining the right temperature, the proper humidity, and of course, the right diet. It is also important for you to be able to spot any problems just as they are developing, so you can correct them right away. Maintaining a healthy shell for your tortoise is not at all that complicated, but there are plenty of ways to screw it up, and the results can be devastating for your tortoise.
A deformed shell can be especially problematic for your tortoise, as they will be living with the consequences for the rest of their long lives. Of course, if you know what to do, they can live exceptionally long and healthy lives, and their healthy shells can stand as a testament to that.
What Makes Up A Tortoise’s Shell
A tortoise’s shell is more than just protection, it is actually part of the animal’s skeletal structure. For most animals, their spine, ribs and breastbone are separate from each other, capable of independent movement. Tortoises, on the other hand, have all of these bones fused together to form a single structure. The shell itself has two parts: the plastron and the carapace. The carapace forms the top of the shell and the plastron forms the breast or the bottom part.
Although the shell itself is hard, what you are touching when you hold your tortoise isn’t actually the bone itself. Covering the bone is a thick layer comprised of skin, scales and keratin, the same material that makes up your fingernails and hair. Aside from that, there is also a rich collection of nerves and blood vessels all across the shell’s surface.
A tortoise’s shell is divided into sections known as scutes. As your tortoise grows older, newer, bigger scutes grow from underneath the old one. Scutes are an important indicator as to whether your tortoise’s shell is healthy or not. Observing how they grow can give you an idea if you need to make adjustments to your husbandry.
Healthy tortoise shells tend to be smooth, with the individual scutes as flat as possible. There are some species that are an exception to this rule, but most of the time, a smooth, domed shell is a good indicator of health. In the case of severe pyramiding, the scutes can grow in an abnormal way, hence deforming the shell, and giving your tortoise a hard time while walking.
How to Maintain a Healthy Shell
Just like any living being, the best place to start if you want to raise a tortoise with a healthy shell is their overall lifestyle. If you have an animal whose needs aren’t met, then their shell, just like the rest of their body, wouldn’t develop properly. It’s even more important to work on a healthy shell if you have younger tortoises, who have a lot of developing to do. Whether that development turns out well or not ultimately depends on your husbandry.
Here are some of the things you need to look out for in order to maintain a healthy shell for your tortoise.
One aspect of tortoise husbandry that has the biggest effect on your tortoise’s shell is their diet. Because a tortoise’s shell is composed mostly of bone, it takes a lot of calcium to maintain not only its overall shape, but also its strength. As such, it’s important to feed your tortoise with a lot of leafy greens that are rich in calcium and low in phosphorus. It’s also important to have their diet be low in protein and high in fiber.
If you are unable to find food that is rich in vitamins or minerals, a good option to try are reptile supplements such as calcium or a cuttle fish bone. If you are wondering if you should give your tortoise calcium we have two an in depth article on these subject to help you out.
Of course, just as important as what the tortoise eats is how often they eat. Overfeeding your tortoise can be just as bad as underfeeding them. Hatchlings that are being fed too often grow unnaturally fast. This can lead to their shells being unable to catch up with the sudden growth, and you’ll end up with gaps between the scutes, exposing tissue underneath. Power-feeding your tortoises could also lead to severe pyramiding, the effects of which we will talk more about later.
Hatchlings can be fed multiple times a day, but as they get older, you can start feeding your tortoise once a day. Adults can be fed every 2 to 3 days.
Tortoises, just like most reptiles, are ectothermic, or cold-blooded. This means that they can’t produce their own body heat, instead relying on the environment for heat regulation. Basically, your tortoise can only get as warm as the environment lets it. If your tortoise gets too cold, they stay cold, and this can severely affect your tortoise’s growth.
Lower than required temperatures affect your tortoise’s digestion, hence dampening their ability to absorb vital nutrients for healthy growth. Colder temperatures also discourage your tortoise from moving too much, making them miss out on much-needed exercise.
Temperatures for your tortoise enclosure should be maintained at 75 °F at the coolest, and up to 105 °F at the warmest. You can maintain this temperature range using heat bulbs but if you want a more stable source of heat, then you can also use heat mats instead. Check out are article on the the best heat lamp for your tortoise to see what we recommended.
Just as important to healthy shell growth as temperature is the humidity. Tortoises tend to prefer humid areas, given that they can absorb moisture through their skin. Humidity itself is particularly important for hatchlings, as higher humidity lowers the risk of your tortoise developing pyramiding. Feeding your tortoise too much in arid environments can cause abnormalities to how your tortoise’s shell develops.
Of course, it can be difficult to maintain humidity for the entire enclosure, especially if you live in a particularly arid place. A good way to go about this problem is to simply focus in smaller areas of your tortoise’s habitat at a time, namely, the hides. You can place sphagnum moss under the hides and spray them daily. This allows you to maintain a high enough humidity in places where your tortoises would hang out most often.
Now, just as bad as having low humidity is keeping it too high. High humidity can be problematic, especially for tortoises that are used to living in arid environments. Tortoises can suffer from respiratory infections, such as pneumonia, which can be fatal. Fungi and certain bacteria can also thrive in humid areas, which can infect your tortoise’s shell. Both of these can hamper your tortoise’s growth, making them develop deformities on their shells.
Humidity in your tortoise enclosure should be around 40% – 60% for desert species, and 60% – 80% for forest species. The hides themselves should have humidity of at least 75% – 85%. Hatchlings can tolerate higher humidity levels.
If you want to know more about the right humidity for your tortoise we have you covered with are article on tortoise enclosure humidity.
You might be surprised to learn that proper lighting can also have an effect on your tortoise’s overall growth. UV light in particular is especially important. UV light not only helps your tortoise absorb calcium, which is a vital mineral for healthy shell growth, it can also encourage them to be more active.
Sunlight is the best source of UV, but if that is not an option where you live, then you and your tortoise will just have to settle for artificial lighting. Now, when you are out buying UV bulbs for your tortoise, you will encounter two different terms, UVA and UVB. Both are very important and depriving your tortoise of either can cause developmental issues.
UVA is a type of UV light that encourages a tortoise’s normal daytime behavior, like foraging for food, walking around, and mating. No UVA means your tortoise will likely become lets active, having very little exercise.
UVB on the other hand is responsible for helping your tortoise produce vitamin D. Vitamin D is an important vitamin that helps your tortoise’s bones absorb calcium more effectively. So, more calcium means a healthier, stronger shell.
Most commercial UV light bulbs nowadays do produce both UVA and UVB, but it’s still possible to buy bulbs that produce these separately. It’s always a good idea to check the box if your bulb is producing the right kind of UV lighting.
Common Problems Concerning Tortoise Shells
Like we’ve said before, a healthy shell is a good indicator that your tortoise itself is healthy. It is also a good indicator of how good your husbandry is. Of course, tortoises can be hardy creatures, and a few lapses here and there in your husbandry will not automatically kill them. If a problem is big enough, however, that you start finding noticeable damage to your tortoise’s shell, then your husbandry needs to be adjusted.
Here are some of the most common problems that affect tortoise shells in captivity.
Shell Rot / Septicemic Cutaneous Ulcerative Disease (SCUD)
Septicemic cutaneous ulcerative disease, most commonly known as shell rot, is a condition where your tortoise’s shell develops ulcers as a result of a bacterial, viral or fungal infection. In mild cases, the keratin layer of the shell starts peeling off. In more severe cases, the ulcers themselves can go as deep as the bone. The infection itself can also spread to the blood stream and may end up fatal if not taken care of early.
There are two types of shell rot that affects tortoises, dry and wet. Dry shell rot is usually more manageable. Applying diluted betadine or antifungal cream, depending on the type of infection, should be enough. Wet shell rot is a bit more problematic to deal with. This type of shell rot not only produces ulcers, but also oozes liquid discharge, and has a pungent smell.
Shell rot is the result of unsanitary habitat conditions, too much humidity, or both. Because shell rot is caused by microorganisms attacking your tortoise’s shell, a good way to prevent it from happening is to simply clean your tortoise enclosure regularly. It’s also important to keep the humidity levels in check.
Pyramiding is the condition where the individual scutes on a tortoise’s shell is raised. This is a problem most commonly associated with captive tortoises and is not that common amongst wild animals. Not all pyramiding is associated with bad husbandry, since any tortoise in captivity will develop them. It does become a problem when the pyramiding itself is so bad that it can cause deformations on the tortoise’s spine. Particularly bad cases could make it difficult for tortoises to walk normally.
What causes pyramiding specifically is still pretty much debated amongst keepers. But the most accepted theory is the lack of humidity during a tortoise’s earlier years. A diet that is too high in protein can also be a leading cause.
Metabolic Bone Disease
Another condition that can severely affect the development of tortoise shells is metabolic bone disease. This condition not only affects the shell itself but can also cause trouble for the rest of a tortoise’s skeleton, causing brittle and weak bones. This can make it difficult for your tortoise to support their own body weight. On top of severe skeletal deformities, the shell can also turn rubbery and soft.
The main cause for metabolic bone disease is the lack of calcium in a tortoise’s diet. The lack of UV light, which helps a tortoise produce vitamin D to absorb calcium is also a huge factor, including the consumption of too much phosphorous.
Metabolic bone disease is often fatal if not taken care of early. It’s also especially problematic for younger tortoises, since they require a lot of calcium to help with their rapid growth.
If your worried about metabolic bone disease you can learn more about it with our article on treating metabolic bone disease in tortoise.
Keeping your tortoise’s shell healthy is an important responsibility for any tortoise keeper. Failure could mean a tortoise that will live a tragically short life full of pain. Luckily, however, maintaining a healthy shell is as simple as meeting their most basic needs. You will have a healthy animal that will spend its long life thanking you for it.