Do reptiles have a backbone?
Yes, all reptiles do have a backbone. They have a backbone because they all are vertebrate animals.
Another broad reason for reptiles having a backbone is because they are Chordates and belong to the Sub-Phylum Vertebrata and Class Reptilia of the Animal Kingdom.
Reptiles are Chordates and so are included in the Phylum Chordata of the Animal Kingdom and so are characterized by the presence of the notochord (a skeletal rod) with a dorsal tubular nerve cord (spinal cord and brain).
Vertebrates are all those animals that belong to the Sub-Phylum Vertebrata and are known to have a vertebral column which is also known as the backbone.
The backbone which is the vertebral column is made up of many small vertebrae (small bones) joined together to form the long backbone coming out from the neck to the base of the tail.
Each of the vertebrae of the backbone is joined with a pair of ribs, one on each side forming the rib cage.
The backbone is located at the mid-dorsal side of the body, and gives the body of the reptile the flexibility and the support.
The more the vertebrae (small bones) in the backbone the longer is the backbone and the more flexible it is for the movement of the body.
Just take the example of snakes, which are reptiles. Snakes do have between 200 to 800 vertebrae making up its backbone (vertebral column) depending on its length and species type.
So, Snake’s body is very flexible and they can crawl super easily due to the many vertebrae (small bones that form the backbone).
Do reptiles have a skeleton?
Yes, of course, reptiles do have a skeleton. The backbone (vertebral column) is a part of the skeleton system of the reptiles.
The skeletal system of the reptiles includes the skull bones, whole backbone, ribs and sternum, pectoral girdle, pelvic girdle, forelimb and hindlimb bones, and many other tertiary bones.
Now the skeleton system and the presence of various bones may differ from species to species in the case of reptiles.
Just like snakes don’t have any limb bones, they also do not have pelvic girdle and pectoral girdle.
On the other hand, the reptiles like lizard have pelvic girdle, pectoral girdle, and limb bones.
Most reptiles have seven mobile cervical vertebrae including a three-part atlas and axis. The
number of cervical vertebrae in snakes remains unresolved with some authors identifying just two (atlas and axis) vertebrae, others identify three, other investigators claim seven or eight, and yet other authors claim as many as 18 cervicals.
On the other case, if you see, all turtles have eight cervical vertebrae. Crocodiles also have eight cervical vertebrae.
Reptiles vary in whether they have single or two-headed ribs. Chelonians like turtles and tortoises are reptiles that appear to have single-headed ribs that align at the junction of two vertebral bodies.
So, it is clear to you that not all reptiles have the same skeleton system. In some reptile species, some bones may be present, and in others, some of the bones may be absent.
So, if you want to study the proper skeleton system of the reptiles then you do need to study each of the species distinctly as the reptilian skeleton system varies majorly between the various species.
So, Do reptiles have a skeleton? Yes, reptiles do have a skeleton but the bones of the skeleton distinctly varies from species to species.
What actually defines a reptile?
Reptiles are all vertebrate animals of the Class Reptilia that includes snakes, lizards, crocodiles, turtles, and tortoises.
They are distinguished as cold-blooded animals, by having dry scaly skin, and typically laying soft-shelled eggs on land.
They are cold-blooded, terrestrial, or aquatic air-breathing animals. Their body is divisible into the head, neck, trunk, and tail and their body skin is covered with horny scales or scutes.
They have 2 pairs of limbs (forelimb and hindlimb) with five digits in each of the limbs. Digits are with horny claws.
However, in some reptiles like those in some lizards and all snakes lack limbs. So, they generally move by slithering or you can simply say by crawling.
Their mouth is located at the anterior end of the body, and the anus at the base of the tail at the posterior end of the body.
Their mouth has jaws with simple conical teeth. Teeth are replaced by horny beaks in turtles and tortoises.
They respire by lungs throughout their life. Seperate male and female individuals are present in reptiles.
They show internal fertilization and the fertilized eggs are laid on land which look very large and are covered with a leathery shell.
Above all reptiles are vertebrates and so they do have a bony endoskeleton with a vertebral column which is also known as the spine or backbone with ribs attached to it.
The vertebral column in most lizards and crocodilians is differentiated into cervical, thoracic, lumbar, sacral, and caudal regions.
What is the function of backbone in reptiles?
The most important function of the backbone in reptiles is the protection of the spinal cord which is inside the backbone.
The spinal cord functions primarily in the transmission of nerve signals from the brain towards the body.
The backbone also provides the rigidity to the body and attachment for the various skeletal muscles. The proper coordination of the skeleton with the skeletal muscles helps in the systemic movement of the body using the limbs to walk or the outer scales of the body to slither.
An additional function of the backbone is to equally transmit the body weight and the balance while the reptile is moving or when it is in the position of rest.
Reptiles travel along the ground, up in the trees, through water, and underground very easily and rapidly. Some snakes can burrow and can travel almost with ease through the existing holes under the soil or rocks. All thanks to the flexible backbone.
The tail of the reptiles has the caudal vertebrae joined together forming the basal part of the backbone. The caudal vertebrae support the tail part and help in balancing the body perfectly.
Just for instance, some reptiles like the Gila monster uses the tail to store energy during periods when food is scarce. So, supporting the tail is necessary.
Others like the various species of chameleon use its tail as the fifth foot, to hold onto limbs when climbing.
Some snakes also have tails that enable them to hold onto branches or vines of trees to assist them in climbing trees.
Vertebrates like retiles have certain features in common. That is they have their backbone made out of bones, and a hollow dorsal nervous system that consists of the spinal cord.
This consists of an anterior brain enclosed in the skull and a spinal cord protected by the backbone.
Reptiles have 15 to hundreds of ribs attached to each of the vertebrae of the backbone, almost the whole way from the neck to down their body, to protect the internal organs.
Thus, the backbone gives support and socket to hold the ribs for protecting the sensitive internal organs from getting crushed during the various physical activities.
What is unique about the reptile skeleton?
The most unique thing about the reptile skeleton is that it’s more flexible, elastic, and at the same time very rigid. Their skeleton system is so flexible that they can increase their size and width of the parts of their body when they swallow a large meal.
They developed larger skeletons that could hold larger organs and help them increase in size.
Just take the example of snakes. They can swallow their food items much bigger than their own head and even bigger than their whole body.
They can highly and elastically expand their jaws as the mouth of a snake is capable of being widely opened by the free articulation of the lower jaw.
So, not only their skeleton but the skeletal muscles as a whole are so flexible and elastic giving the proper free articulation to the body for easy movements and stretchability.
Another thing to notice is that the reptiles like lizards and all others have their limbs shifted to the bottom of the body.
Unlike the amphibians, that have legs on the sides, reptiles have legs that are directed down towards the ground, lifting the body upwards and thus protecting the soft internal organs from getting damaged.
This effectively helps the reptiles to pick their bellies off the ground and helps them move more efficiently. Although, this doesn’t apply for snakes who don’t have any limbs and so slither placing their belly on the ground.
Their skeletal bones act as levers, provide protection, and in some cases form bony armor. Bones are tough and resilient material yet is vulnerable to injury or disease.
Just like the other animals, reptiles bones also directly interact with muscles via their tendons and through their combined functions skeletal form having systemic interactions with the environment.
In young rapidly growing reptiles often there are many more vascular channels in the bone than in the bone-forming mature skeletons.
Another thing is that the skeletal system broadly varies. For example, if you see, heavy-bodied reptiles tend to have more compact bones that the light-bodied species.
Another example is that the aquatic species tend to have heavier bones than their terrestrial counterparts.
Endoskeleton Vs. Exoskeleton of Reptiles
➜ Endoskeleton of Reptiles
The endoskeleton is the internal skeleton such as the bones that make much of the whole skeletal system of the reptiles.
The main function of the endoskeleton is to support the body internally and provide the balance to the body and protection to various internal organs.
During early embryonic development the endoskeleton is composed of notochord and cartilage. The notochord in reptiles is replaced by the vertebral column and cartilage is replaced by bones.
The endoskeleton includes the backbone, limb bones, skull, tail bone, pectoral girdle, pelvic girdle, ribs, and all other bones that are included in the skeleton system of the reptile.
➜ Exoskeleton of Reptiles
The exoskeleton is the external skeleton that exists on the outside of the reptile’s body.
The exoskeleton is usually hard and rough with spines sometimes that provides support and protects the muscles and soft tissues or organs of the body from the outside.
In very simple words, an exoskeleton is an exterior hard covering which is not made of bones and that covers an animal’s entire body, giving it support and protection.
During the embryonic development stage of the reptile, the exoskeleton develops from the ectoderm layer. The ectoderm is the tissue layer that covers the outside of the embryo.
The exoskeleton of reptiles is made up of horny epidermal scales, shields, or scutes. These scales, shields, or scutes are horny and rough and are located on the outer covering of the skin surface.