Turtles have backbones because they have vertebrae. Unlike humans and other animals with backbones, the backbone of turtles is comprised of two parts; the shell that forms an exoskeleton and a bony endoskeleton. The shell in turtles is very tough and is fused with the spine and rib cage.
Let’s talk about the turtle’s backbone in more detail now.
A Closer Look At The Backbone Of Turtles
You may already know that animals are classified into vertebrates and invertebrates.
Vertebrates have backbones or spinal columns. Meanwhile, invertebrates lack a bony skeleton or backbone.
Animals that belong to the lower divisions of the animal kingdom are invertebrates.
Meanwhile, fish, amphibians, reptiles, birds, and mammals are vertebrates.
Turtles are reptiles. So, technically they have backbones. However, their backbones are different from other animals.
The ribs and backbone are fused to form the upper portion of a turtle’s shell.
So, it is a single rigid unit that is non-pliable. Hence turtles cannot bend or move their shell.
Another unique feature of turtles is that their shoulder blades are fused with their shells.
However, turtles have small, flexible vertebrae in the neck and tail that allow them to move these parts.
Now, the tough, bony shell of a turtle has two layers. The outer area is formed of a protein called keratin.
The keratin is arranged in the form of patches called scutes.
The number of scutes will usually remain the same throughout a turtle’s life.
However, these scutes develop more rings as the turtle ages. So, the rings within the scutes are an indicator of the turtle’s age.
If you closely observe a turtle shell, you will notice that it’s made of two parts.
There is an upper dome-shaped structure and a flat lower structure.
The upper part is called the carapace, while the lower half is the plastron.
The carapace and plastron are fused along a bony bridge that appears on the side of the turtle.
This bridge extends from the forelegs to the hind legs in a circular fashion.
The shell will also have spaces for the turtle’s head and limbs.
When the turtle withdraws its head and limbs into the shell, the gaps for the head and limbs remain exposed.
However, some turtles have a hinge in the plastron.
It allows them to pull the upper and lower halves of their shell together.
This helps to minimize the gap where the head and limbs appear.
Can Turtles Live Without Their Shell?
We already saw that the shell is the backbone of a turtle. Hence, it’s an integral organ for this animal.
You may already know that turtles retreat into their shells when they sense danger.
But did you know that their shells were not originally meant to be protective organs?
Studies reveal that ancient turtle species used their shells as defensive organs.
They would stay hidden inside their shell and wait for prey.
When their prey came close, they would quickly shoot their heads out and catch it unaware.
However, this organ later evolved into a protective armor that shielded the turtle from danger.
Although shells are protective organs, remember that they are made of living bone.
The shell has nerves, blood supply, and tissues.
Hence, a turtle can feel it when you touch its shell. If the shell is broken or injured, it pains.
Since the shell is fused to the rest of the body, a turtle cannot live without its shell.
Severe damage or injury to the shell can even lead to the death of the turtle.
Hence, any stories you may have heard of a turtle abandoning its shell are purely fictional.
Now, the good news is that a turtle can outgrow small shell injuries.
Since it is made of living material, the shell can repair itself to a great extent.
However, recovery is very slow. Hence it may not be able to survive if the shell is severely impacted or fractured.
Do All Turtles Have Backbones?
Technically, all reptiles have backbones. The shell forms the backbone of a turtle.
Since there are different varieties of turtles, their shell structure and shape will differ from one species to another.
Let’s look at the most common varieties and see how their backbones are.
Do Box Turtles Have Backbones?
Box turtles have backbones. Their vertebrae are in the center of their shells and fused to the rest of their body.
It is rigid and elongated along the length of the shell.
However, the vertebrae will be small and flexible in the neck and tail regions. This is to allow the movement of these organs.
Do Red-eared And Yellow-bellied Slider Turtles Have Backbones?
Red-eared and yellow-bellied sliders have fused ribs, and the backbone is attached to their shell.
The shell also has horn-like keratinous structures called scutes.
The upper and lower parts of their shells are joined by a bridge that runs along their side.
Do Painted Turtles Have Backbones?
There is a raised line on the shell of a painted turtle. It extends from head to tail and forms the turtle’s backbone.
The shell is also attached to the shoulder blades. In painted turtles, the shell consists of 60 bones.
Do Sea Turtles Have Backbones?
Did you know that sea turtles are one of the world’s oldest vertebrates?
Their backbones are fused to the shell, forming an integral part of their body.
Most sea turtles have bony shells composed of fused and wide ribs and bones.
If you look at the shell closely, you will notice a raised line along the center that extends from head to tail.
This is where the backbone of the animal is located.
The shell is covered with horny plates called scutes in most sea turtles.
The pattern and number of scutes will usually vary from one species to another.
While most aquatic and terrestrial turtles can at least partially withdraw their head and limbs into their shells, sea turtles are unable to do so.
Their shells are not big enough to conceal their heads and limbs and don’t serve to hide them from danger.
Do Leatherback Sea Turtles Have Backbones?
Leatherback sea turtles have a unique shell structure.
Unlike other turtles, their shell is soft and rubbery instead of hard and bony.
However, these animals also have a backbone beneath the shell.
In leatherback turtles, the spine is not fused with the carapace.
Instead, the backbone is covered with leathery skin and supported by tiny bones.
This special adaptation allows leatherback turtles to swim in the lowest depths of the ocean, where the pressure is extremely high.
The water pressure at the lower depths of the ocean would crush a rigid, bony shell.
However, the flexible leathery shell of a leatherback turtle can endure this high pressure.
Do Snapping Turtles Have Backbones?
In snapping turtles, the backbone is fused with their shell.
The central portion of their carapace is raised because it is where their spine is located.
Their shoulder blades are fused with their rib cage. Snapping turtles also have horns on their shells as a special structure.
Snapping turtles cannot fully retract their heads and limbs into their shells.
Hence, they tend to become aggressive and snap when intruders or enemies threaten them.