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My Turtle’s Shell is Soft: Common Pet Problems

If your turtle’s shell is soft you are dealing with a common but serious problem for pet reptiles. Unless your pet has a natural soft turtle shell it may have a metabolic disorder that is fatal if not treated. The shell of a turtle is also itself a topic all pet keepers should be well informed about. So let’s take a moment to discuss shell issues in pet turtles.

Why is My Turtle’s Shell Soft?

turtles shell is soft

A healthy Red Ear Slider shell (or that of any other turtle) should be firm and hard. It should not have any give when held – but you also don’t need to squeeze your turtle to test this. 

Turtles do not enjoy being handled and don’t really become domesticated over time. But handling your turtle should be the first thing you do when you think about buying one. 

If you find that a turtle’s shell is soft I recommend choosing another one. Soft shells are a sign of vitamin deficiencies. While they can be treated over time these diseases often affect the bones as well as the shell.

 A turtle may end up dying before you can remineralize their shell and bones through nutritional supplements.

Do You Have a Softshell Turtle?

It’s worth mentioning that there are a group of turtles that have a natural soft shell. A soft shell turtle shell feels leathery and has a lot of give. In the center the turtle does have the same hard parts (scutes) of other turtles. 

The lighter form of a soft back turtle allows it to swim and move on land much faster than other aquatic turtles.  Soft Shell Turtles belong to the family Trionychidae. They are common in pet stores and make good pets but they do look very distinct. You won’t confuse a soft shell turtle with other aquatic turtles.

The Structure of a Turtle’s Shell

A turtle’s shell has several structural components to it. The portion that runs along the back of the turtle is called the carapace. It is an outgrowth of the backbone and fused ribs of the turtle that is its main source of protection.

But when you touch the carapace it won’t feel quite like bone. That’s because the carapace is covered in a layer of horny scales called scutes. 

Scutes are actually made of keratin; the same fibrous protein that is found in your own skin, nails, and hair. The feathers of birds and even fish scales are also made of keratin, showing its versatility as a structural material.

The bottom shell (plastron) that runs along the turtle’s belly is smoother in feel and glossy looking. By comparison the carapace will feel harder and often have ridges or even spikes. 

The carapace is the protective shell that prevents predators from attacking the slow, otherwise defenseless turtle. In many species it will be somewhat harder than the plastron – but not always.

Just so you know, turtles also shed their shells. Not the entire thing, mind you. No one has ever seen a naked turtle. They shed the upper layers of their scutes as they grow. 

The worn outermost layers flake away, revealing a fresh, tough layer of unworn keratin scutes. So long as the new shell layers are not soft, shed scutes are no cause for concern for pet turtle keepers 

Are Turtles Born With Their Shells?

All turtles are born with their shells. The shell develops while the baby turtle is still inside its egg. Turtle shells are made of the backbone, sternum, and ribs – same as most vertebrate animals. But turtles evolved so that these bones fuse to form a new structure.

One reason a turtle’s shell is soft is because it is a newly hatched baby. A baby turtle fresh from the egg may have a somewhat soft shell at first. It needs to feed and build up enough calcium to harden its shell. This can take a few weeks to months, depending on the species of turtle. 

Unhealthy Turtle Shell Due to Metabolic Bone Disease

Assuming you don’t have a baby turtle fresh from its shell or a true soft shell turtle, then your turtle’s soft shell is due to a disease or disorder. By far the most common reason is metabolic bone disease.

Dietary Calcium and Bone Disease

Metabolic bone disease is a serious disorder affecting thousands of pet turtles in the trade. Dietary calcium is an important component to the shells and bones of all animals, including us humans. Turtles need access to calcium to build up their bones and maintain shell integrity.

When the body of a turtle does not get enough calcium it will first start to reinforce its shell by pulling the metal from its bones. Once the bones start to become depleted in calcium the shell will also soften. This version of metabolic bone disease is known as nutritional secondary hyperparathyroidism.

If the turtle still isn’t given enough calcium it will soon die as its muscles and organs all rely on bones for structure and function. Bones will also start to collapse on themselves, putting pressure on the interior and disrupting blood circulation. 

The legs will swell as the weight of the shell presses on the body cavity, forcing fluid outward. Even though the shell has lost some weight from calcium deficiency it is still quite heavy. And without proper support from the turtle’s skeleton the shell’s weight will start to smother the turtle.

Young turtles are even more prone to metabolic bone disease than adults because they are growing faster and need more calcium in their diet. The damage is also more often permanent if left untreated in young turtles. 

Metabolic bone disease is still reversible if caught in time. But a kink to the tail, spine, or shell deformities may become permanent once calcium is reintroduced to the diet of the baby turtle pet.

Ultraviolet Radiation and Vitamin D3

Dietary calcium is very important for turtles. But they also need a second component: vitamin D3. While it is called a vitamin, D3 is actually a hormone that regulates calcium uptake in the body of many animals.

The main source of vitamin D3 is a precursor chemical that converts to the nutrient when the skin of an animal is exposed to sunlight. Ultraviolet radiation is the spectrum of the sun that does the conversion; UVb, to be precise.

In any turtle tank setup you need to include UVb lighting as part of their basking light setup. Tank setups without UVb are the main reason you will see unhealthy turtle shell symptoms form in pet reptiles.

Symptoms of Metabolic Bone Disease in Turtles:

  • Swollen legs due to lack of skeletal support 
  • Carapace is soft and has slight give when touched
  • Spinal and tail malformed (kinks, curves, etc)
  • Turtle has trouble lifting head, moving, refuses to swim
  • Seizures; paralysis and eventual death

Turtle Soft Shell Treatment

Soft back turtle disorders are often caused by metabolic bone disease. This disorder is very serious but it is also reversible if caught soon enough. To treat the disorder you have to address the calcium deficiency that caused it. 

That means adding calcium supplements to their diet and ensuring they have access to Vitamin D3 through ultraviolet lighting of the proper spectrum.

Dietary calcium is simple enough to add. Vitamin booster powders can be found at any local pet store formulated specific to the needs of turtles. Many also have dietary vitamin D3 added as well. 

The jury is still out on how beneficial vitamin D3 is for turtles to eat since no one knows if they can absorb it or not. But it does not hurt and may quicken the healing process. So try to buy a calcium blend that also includes vitamin D3 if your turtle’s shell is soft.

Make sure that you add UVb bulbs to the light setup of your turtle tank. They should run along with your daytime visible light and infrared (heat) lamps. UVb ensures that your turtle will produce vitamin D3 when it basks. It will then metabolize calcium and start to build back up its bones and shell.

That said, deformities may or may not be permanent. The turtle has no way to “reinflate” or straighten out its shell if the metabolic bone disease has gone on for too long. Internal bones may also suffer permanent damage and affect how the turtle swims or walks for the rest of its life.


If your turtle’s shell is soft it may have a serious disorder that you need to treat: metabolic bone disease. The disorder is caused by improper care – too little dietary calcium and/or a lack of ultraviolet radiation in its lighting. 

You can stop and reverse the disorder but damage can be permanent if not caught early enough. So make sure that you have the right setup from the start when shopping for a new aquatic pet turtle.

More Frequently Asked Questions about Why My Turtle’s Shell is Soft

Turtle soft shell treatment is a complex topic and I hope you won’t ever have to deal with it. But those that do may have questions about the problem. Here are the ones I most frequently receive.

Do Turtles Have Bones?

Turtles are vertebrates and they do have bones. The shell is a fusion of bones from the backbone (vertebra), sternum (chest bone), and ribs. The carapace is the upper portion of the shell and it has scutes made of keratin covering it. These scutes protect the bone of the carapace. They absorb all wear and flake away over time to reveal fresh new plates of keratin.

How to Treat Turtle Shell Soft Disorders?

Dietary calcium and ultraviolet light exposure are needed to treat metabolic bone disease. Even if the food you feed your turtle has calcium it won’t be able to absorb it if it’s lacking vitamin D3, which comes from UVb exposure. So if your turtle’s shell is soft, add extra calcium and vitamin D3 through a powder supplement. And make sure your lighting setup has new UVb bulbs at the right distance from the basking zone.

What is a Soft Shell Turtle Shell Made Of?

A soft shell turtle shell is similar to that of other turtles. They do have a hard carapace section but it is confined to the very center of the shell. The turtle also has no keratin scutes covering the carapace. Leathery skin grows from the carapace out to the sides of the turtle. This minimal shell design allows soft shell turtles to move faster in the water and on land compared to other aquatic turtles.

Jason Roberts
About Jason Roberts
Jason is an aquarium fanatic that has been a fish hobbyist for almost three decades.