In the fauna of our planet, reptiles, numbering about 6 thousand species, are represented by several biological groups. One of them is the Turtle squad. Contains 328 species grouped into 14 families. This article will study the structure of the turtle's skeleton, as well as the features associated with the aquatic-terrestrial lifestyle of this animal.
Anatomical structure
Representatives of the detachment live in the steppes, foothills of Pakistan and India, in the deserts of Turkmenistan, Syria and Libya. Like other animals belonging to the reptile family, in the structure of their body, as well as in the processes of life, a number of idioadaptations to a dry and hot climate can be found. Among such devices, dense leathery integuments, the absence of mucous glands, the presence of horny scales and scutes are distinguished. These formations consist of fibrillar proteins - keratins. Their function is to increase the mechanical strength of the outer covers.
Since land turtles, such as the steppe,Central Asian, feed on fairly hard plant foods, they have a beak on their head - a kind of process that has sharp edges with teeth. Turtles tear off parts of plants with them and rub them with tuberculate protrusions. There are also eyes on the head. They are limited to three eyelids: lower, upper and third. Presented in the form of a leathery film, covering the eye only halfway. All turtles have well-developed binocular vision and are excellent at navigating their environment.
Departments of the turtle skeleton
To answer the question of whether a turtle has a skeleton, remember that the body of a reptile is anatomically divided into 4 parts. It consists of a head, neck, torso and tail. Consider the structure of the turtle in section. So, her spine consists of 5 sections: cervical, thoracic, lumbar, sacral and caudal. The skeleton of the head is completely bony. It is connected to the neck through two movable vertebrae. In total, the turtle has 8 cervical vertebrae. The head at the moment of danger is drawn into the shell, due to the presence of a hole in it. Land reptiles perceive low frequency sounds. Turtles are classified as "silent" animals, as their vocal cords are anatomically poorly developed. Therefore, they make a hiss or a squeak.
Structure and functions of carapace
Continuing to study the turtle's skeleton, consider the upper part of its shell. It has a bulge that looks like a small bell. In land turtles, it is especially high and massive, in water turtles it is flatter,streamlined shape. The carapace consists of two layers. The outer one contains keratin scales - shields, and the lower one has a complete bone structure. The arches of the vertebrae of the lumbar-thoracic region and the ribs are attached to it. The coloration and pattern of the horny shields of the carapace are used by taxonomists to determine the species of animals. It is because of the shell that turtles have been and remain the object of fishing. It is used to make spectacle frames, cases, knife handles. The shell has several openings into which the animal draws its head, limbs and tail at the moment of danger.
Plastron and its meaning
The lower part of the shell is called the plastron. Between it and the carapace is the soft body of the animal. Both of its halves are united by a bone shell. The plastron itself is an anatomical derivative of the forelimb girdle and ribs. It is, as it were, "soldered" into the body of a turtle. Terrestrial forms have a massive plastron. And in marine life, it is reduced to cruciform plates located on the abdominal part of the body. As a result of growth, concentric lines form on the scutes of the shell. According to them, herpetologists can determine the age of the turtle and its state of he alth.
Characteristics of the skeleton of the belts of the front and hind limbs of the turtle
The skeleton of a turtle, the diagram of which is shown below, indicates that animals of this species belong to reptiles. They have the bones of the girdle of the forelimbs attached to the spine: the scapula, the clavicle and the crow's formation. They are located in the middle of the chest. The blade is connected tocarapace by a muscular fold at the location of the first vertebra. The hind limb girdle consists of the pubic, iliac, and ischial bones. They form the pelvis. The tail section consists of many small vertebrae, so it is very mobile.
Features of the structure of the limbs of land turtles
The forelimbs of reptiles consist of the shoulder, forearm, wrist, metacarpus and phalanges, which is similar to the skeleton of other classes of terrestrial vertebrates. However, there are differences in the structure of the bones of the forelimb. For example, the tubular bone of the shoulder is short, and their number, forming the wrist, is less than in mammals. The hind limbs also have anatomical features. The femur is very short, and their number in the foot is also reduced. This is especially noticeable in land turtles: box, red-eared, steppe. Since they move along the surface of the earth, the bones of the phalanges of their fingers experience constant mechanical stress. Thus, the turtle's skeleton has the necessary idioadaptations to help it adapt to its habitat.
Red-eared turtle: structure and features of life
Among all other species, this animal is the most popular as a pet. The structure of the red-eared turtle is typical for freshwater forms. Its head is well mobile, the neck is long, the carapace is represented by a green carapace, and the plastron is yellow. Because of this, the turtle is often called the yellow-bellied turtle. limbsmassive, covered with horny shields, ending in claws. In nature, they feed on insects that live in abundance along the banks of rivers, larvae and fry of fish, as well as algae. The female is easy to distinguish from the male: she is more massive and longer, and her lower jaws are larger. These animals breed in the period from late February to May, laying 4 to 10 eggs in sandy pits. Baby turtles usually hatch in July or August.
Land species of turtles
This group of reptiles is represented by such animals as the Central Asian tortoise, listed in the Red Book, Balkan, Panther. There are only about 40 species. The external skeleton of a turtle is the shell. It is very massive, with a highly raised plastron. The animals themselves are quite inactive. The Central Asian tortoise is little dependent on water sources. She can do without it for a long time, eating succulent leaves or shoots of herbaceous plants. Since the animal has to adapt to the dry climate of the steppe or semi-desert, its annual activity is strictly regulated. It is only 2-3 months, and the rest of the year the turtle spends in semi-stupor or hibernates in holes dug in the sand. This happens twice a year - in summer and winter.
The structure of the land turtle is characterized by a number of adaptations associated with life on land. These are columnar massive limbs, the phalanges of which are completely fused, leaving short claws free. The body is covered with horny scales that prevent excessevaporation and ensuring the preservation of water in the tissues of the animal. Thus, the animals are reliably protected by a heavy-duty bone-horn shell. In addition, they can scare away potential enemies with sharp hissing sounds or very rapid emptying of a voluminous bladder. All types of land turtles are long-lived. They can live from 50 to 180 years. In addition, they are highly adaptable and durable.
However, let's not forget that 228 species of turtles need protection and are on the verge of extinction. For example, the range of the green turtle is rapidly decreasing. It serves as an object of fishing, as a person eats its meat. Due to urbanization and a decrease in the area of natural habitat, the number of animals is declining every year. The question of the expediency of keeping turtles in human dwellings remains controversial, even if they are localized in specially equipped terrarium conditions. A negligible number of these animals survive in captivity to their biological age. Most of them die from an ignorant and irresponsible attitude towards them.
