Turtles are reptiles, which are distinguished from other vertebrates by the structural features of the skeleton. It is believed that these unique animals lived 220 million years ago, which makes them one of the oldest reptiles, older than lizards, snakes or crocodiles. Modern science knows 327 species of turtles, and many of them are endangered.
Skeleton of a turtle: structural features
The turtle skeleton has distinctive features compared to any other vertebrate, in which the shoulder blades are located outside the chest, as in humans, large cats, elephants, goats and monkeys. The carapace of the turtles is part of the bone structure. This means that a protective shell is more than just an outer covering. This is an integral part of the animal’s body. When the skeleton of turtles begins to form, the shoulder blades and ribs become part of the growing shell. The skeleton consists of bones and cartilage.
As a rule, it is divided into 3 main parts:
- skull (cranial box, jaw and hyoid apparatus);
- axial skeleton of the turtle, internal or external (carapace, vertebrae, ribs and derived ribs);
- appendicular skeleton (limbs, chest and pelvic structures).
Land Turtle Skeleton: Spine
The skeleton of a land tortoise includes the spine along with the cervical, thoracic, lumbar, sacral and caudal regions. The cervical is presented in the form of 8 vertebrae, and the first 2 are very mobile. This is followed by 10 trunk vertebrae fused with carapace. In the sacral region are flat transverse growths to which the pelvic bones are attached. Many vertebrae are present in the tail, as a rule, no more than 33. This department is highly mobile.
The skeleton of a turtle, the photo of which is presented in the article, includes a practically completely ossified skull, consisting of the brain and visceral compartment. The teeth as such are absent, in their place are the horn plates, forming a kind of beak. A unique feature of the skeleton of a turtle compared to other vertebrates is that the limbs are displaced under the ribs.
The uniqueness of the structure of sea turtles
The anatomy of a sea turtle is unique in that it is one of the few creatures that have both an internal and an external skeleton. In all species, with the exception of leathery ones, the external frame provides protection and support for internal organs. It consists of a bone membrane, which, in turn, is divided into two halves: the lower and upper armored plastron. Muscles are attached to the inner skeleton. As in land, the spine of sea turtles grows together with the shell.
Long fingers in the limbs form fins, which are used to move in water. They are also used by females to dig egg pits during the nesting period. Sea turtles have no teeth in their mouths. Instead, they have a sharp beak, with which you can crush food. The leathery mouth contains a number of undeveloped spines.
Not all turtles have a hard shell.
In leathery turtles, the spine does not grow together with the carapace and does not have a bone shell; instead, it is covered with hard skin and is supported by a system of tiny bones. These devices allow the turtle to dive to a depth of 1.5 km.
Interesting facts about turtles
- The shell skeleton of turtles actually consists of approximately 50 different bones. Outwardly, it resembles a single continuous shield, and its inner shell consists of several bones and is formed by the fusion of the ribs and vertebrae of the animal.
- From the inside, the carapace is more like the rib cage that the turtle wears outside its body. Depending on the species, the size of the animal, as well as other parameters, may vary. For example, the skeleton of a red-eared turtle is distinguished by the length of the limbs and caudal region, the tail of males is longer and thicker, and the carapace is shorter than that of females.
- The animal is forever confined to its house. It is physical unable to leave it, otherwise it will lose its own spine and chest.
- Thanks to the unusually mobile and elastic cervical vertebrae, the turtle can pull its head out of the shell or, conversely, hide it when it is necessary for protection.
- The shell skeleton of turtles includes a special movable joint, which acts as a hinge and allows you to pull in the entire body.
- Turtle shells are not armor, although they look like tough and impenetrable shields. There are built-in nerves and blood vessels, so if an animal is injured in its protective shell, it can bleed and feel pain.
- In 1968, two Russian turtles visited space and returned safe and sound, only slightly lost weight. In doing so, they showed that any living creature can make a moon trip.
- Despite their innocuous appearance, they can be ruthless predators. A certain type of reptile can grow up to 2.5 meters in length, weigh more than 100 kg and have powerful jaws, a sharply-hooked beak, bear claws and a muscular tail. She lures her prey, sometimes it can even be another turtle, moving its tongue, which looks like a worm.
- An interesting feature of these animals is that in the absence of vocal cords, they can still make sounds. Most of them hiss, although you can hear a peculiar grunt or cluck. The tortoise does this by jerking its head so that the air squeezed out of the lungs comes out with a certain sound.
- They turn into real bloodhounds when excited. The genitals of females are hidden in their rectum, in the cavity near the tail, which is used both for reproduction and defecation. The male easily detects the female by the smell of pheromones secreted inside the cloaca.
- Another interesting fact about the turtle fifth point. It turns out that you can breathe through it! In some species, the rectum is surrounded by a thin membrane through which gas exchange can occur during immersion.
- Several species of turtles can live for more than a hundred years.
- They are not as slow as they used to think about. They are mainly herbivores, so they don’t have to chase their food. They have good, tight shells, so they don’t have to run away from anyone.