Why Do Turtles Have Shells?

Why Do Turtles Have Shells
Written by Emma Watson

In the reptilian world, turtles are a wonderful mystery. Anyone who has ever been fortunate enough to witness one swimming in the wild knows what a breathtaking sight they are. Pet turtles come in a variety of sizes and shapes, but they always have one thing in common, a SHELL!

Many of us have witnessed a turtle sliding its four legs, as well as its head and tail, into its protective shell. However, while a turtle’s shell protects its delicate insides, it wasn’t meant for this purpose. According to an international team of scientists, turtle shell was first used as a digging tool. Also, about turtles, the scientists always have a question in their mind that why do turtles have shells. Why do they need anything on their body that halts their motion a lot?

In this article, we are going to address all your queries regarding the presence of a shell on a turtle. So continue reading and dive deep with me into the mystical world of our pet turtles.

Turtles have shells because they found a very effective way to protect their internal organs. The shells are critically helpful for providing support to the rest of the turtle’s body.

Turtle shells are also used as digging tools. At first, they began as large rib bones and then expanded from there. No doubt they slow the pace of your lovey-dovey turtles, yet they are the safest large, heavy armor any prey in the hoard of predators can wear.

How Do Shells Evolve?

Massive, strong ribs protected the ancestors of the turtle in the early versions of the turtle’s shell. These bones also facilitated buoyancy, or the capacity to rise and fall in the water. If you’ve ever seen a turtle in the water, you’ll notice how much faster they move than they do on land, owing to their buoyant shell.

The rib bones become more complicated and larger over millions of years. This evolution is significant because, unlike other animals with hard exteriors, such as armadillos, a turtle’s shell is a part of the animal’s bone structure, not scales. It’s almost as if their bones are worn on the outside of their bodies.

This is the reason that shell is an integral part of a turtle’s body from which it cannot be separated.

Importance Of Shell For A Turtle

Turtles are the only land animal on this planet with a distinctive shells on their soft bodies. A turtle shell is as much important for its body as a rib cage is essential to humans. In fact, a shell is the rib cage of the turtles that protects all the vital and delicate organs of their body.


The shell protects the turtle and keeps it safe. When turtles are in danger, they retract their head, arms, and legs into the shell. In this way, the shell gives them protection from the predators and other factors challenging its existence.


Turtle is also among the very few animals that breath with their butts. Most land animals breathe by the expansion and contraction of their ribs. This creates a pump that takes air in and out of the lungs. The turtles can’t do this because their rigid shells don’t expand. Instead, they rely on the sheath of muscles within their shells to pump in oxygen through their mouth.


Inside a turtle shell, there is a special feature that helps them hibernating underwater. There is a scaffold-like structure that can store and release chemicals. This structure helps the turtle breathe when there is no oxygen around.

Anaerobic Respiration

Many turtles hibernate under frozen ponds that are starved of oxygen. To survive in such an environment, their metabolism shifts from aerobic to anaerobic. They stop using oxygen and start breaking glucose for their oxygen needs.

This process is known as anaerobic respiration. Lactic acid, a byproduct of this process, can build up in their body and kill them. The shell can absorb lactic acid as well as releases bicarbonate that neutralizes this acid.

Other Situations

Having a shell helps them to survive under critical circumstances. Scientists think that the origin of turtle shells lies in digging. Shells are incredibly useful against predators.

Parts Of Turtle's Shell

The turtle’s shell is made up of many tiny bones, and it is covered by scoots. These are made up of keratin. Eventually, scoots fall off, and new ones take their place. The turtle’s shell is made up of three parts.

The top part is called the carapace, and it covers the back. The carapace is protected by an outer layer of scoots, which are separate sections. These, like your hair and nails, are comprised of keratin.  

The bottom part is called the plastron, and it covers the belly.

The third part is called the bridge, which connects the first two parts.

What Happens If A Turtle's Shell Is Broken Or Injured?

The shell of a turtle serves as its shield and the final defense against many of the world’s dangers. When that tough shell is cracked or fractured, the turtle becomes vulnerable to infection, germs, and animal predation. Though turtles are strong, a severe injury to the shell can be fatal.

Is It Reasonable To Paint A Turtle's Shell?

Painting a turtle’s shell may appear attractive and safe, but it can be harmful to the animal. UV radiation, primarily UVB wavelength, is required by turtles for Vitamin D production, which is required for bone and shell formation. Reptiles, unlike mammals and birds, are unable to produce Vitamin D and must obtain it through their shells. Painting the shell prevents UV absorption, which can weaken and deform the bones and shell. Through the use of proper medications and care, a damaged shell can grow back, but it can take months.


Many people believe that a turtle has a shell for its protection. It is valid to some extent as it protects them from other competitors. A turtle’s shell is created after the broadening of the rib bones, and it makes the chest more rigid. The rigid chest will make it harder for the turtle to breathe or more quickly.

 Scientists started asking why turtles have evolved such an adaptation that makes them easier to catch. After studying fossils of various turtle species, scientists now believe that the actual reason for a turtle’s shell was as a digging tool. It helps stabilize the turtle so it can eat food and water and helping them to move underwater. This helps turtles to survive under typical situations and become the creatures we now know.

I hope this article answered all your questions related to turtles shell and how it is vital for its existence. If you still have any other queries, drop down the comment or contact us. We would be happy to help.