As a result of evolution, the reptile class began to appear to be a great variety in different geographical zones: in the tropics, deserts, caves, in fresh waters and seas. This is an ancient highly organized group of terrestrial animals, which has about eight thousand species. They crawl along the surface of the earth, hence the name of the class. 4 groups belong to reptiles: scaly, turtles, crocodiles and beak-headed. Their development and prosperity are associated with a change in climatic conditions and the spread of the continental climate in the Mesozoic era.
The topic of the article is devoted to the most numerous detachment of the reptile class - the squamous detachment. It should be noted right away that the classification of this group is very complicated and confusing, something new is constantly being introduced or the old is shuffled. Therefore, different sources may have different information.
General characteristics of squad
Scaly (from the Latin squama - "scales") number 6500 species and are considered today one of the most prosperous reptile groups. According to the latest scientific systematization, the squamous squad is divided into 5 suborders: snakes, lizards, iguanas, geckos and amphisbens. Representatives of the squad are settled throughout the planet and do not live only in harsh polar conditions.
In appearance and lifestyle, animals differ from each other, but they also have common features. The flexible body of the scaly ones is covered with horny scales or scutes, which, depending on the type of animals, may differ in color, shape and size. The square bone of the upper jaw has a movable connection with the cranium. Another distinguishing feature is the long tongue, which performs the function of touch and smell.
Flake propagation
Scaly, like all reptiles, are heterosexual animals. Females have paired ovaries and oviducts opening in the cloaca, males have testes and vas deferens. Fertilization occurs inside, in the reproductive ducts of the female. A fertilized egg, moving along the oviduct, acquires protective coatings - germinal and shell. Eggs are laid in warm soil or hatched inside the female until hatching immediately after laying.
Among scaly ones, viviparous species are also found. For example, an adder is an ordinary or viviparous lizard: the fetus inside the mother is connected to her body with a complex system of blood vessels that provide him with the necessary nutrition and oxygen.
Snakes
In honor of these animals, temples were once built and entire cults were created, they were worshiped and idolized, legends and myths were composed. They frighten someone with their appearance, someone arouse interest, the attitude of mankind towards them has always been ambiguous. We are talking about snakes, reptiles squad scaly. This suborder consists of 18 families and totals 2700 species.
The structural features of the snake are a long body without limbs and a small head. Its spine is represented by only two sections - the trunk and tail, the vertebrae of which have a uniform structure. The representatives of this suborder have a cold, unblinking look, their eyes are covered with a transparent protective film and are devoid of eyelids - they are hard to see. Also, snakes cannot boast of hearing, they do not have ear holes, they pick up vibrations of sound from the ground. But all the minuses are compensated by the sense of smell, with the help of which the snakes successfully orient themselves in space and hunt.
Snakes have a peculiar structure of the skull: bones of the oral apparatus, and some bones of the skull are movably connected to each other. The lower jaw has highly extensible ligaments, which explains the ability to completely swallow prey. The teeth of these scaly ones are very well developed, but they cannot chew with them: sharp, thin and bent back. Many snakes have poisonous teeth, they have grooves along which the venom enters the victim during a bite.
Lizards
The lizard suborder is a large and very common group of the squamous class of reptiles (or reptiles). It consists of 13 families, each of which has its own characteristic features: girdle-tails, venomotives, teiids, monitor lizards, gerrosaurs and others. The largest number of species is concentrated in the tropics.
Most lizards are equipped with limbs, but legless species are also found. Unlike snakes, they have a sternum, and the jaw bones are tightly connected to each other. Most lizards have well-developed eyelids and an eardrum. These scaly ones are known for all their involuntary discarding of the tail, which then grows back.
The color of lizards can be the most diverse and performs a protective function, it harmonizes well with the surrounding reality.
Gecko suborder
Not all geckos are classified as a separate suborder of scaly ones, however, some experts still highlight it. The suborder consists of 8 families: scales, carthodactylids, phyllodectylids, geckos, worm-shaped lizards and others. They live in tropical and subtropical regions and for the most part lead a nocturnal lifestyle.
The size of geckos is not more than 10-15 cm, but you can also meet a large individual. These representatives of the squamous squad can boast of their unique fingers, which have special devices, which helps them stay on any vertical surface. We are talking about extended plates with intersecting rows of brushes from microscopic hairs.
Geckos are very peculiar in behavior that is not typical of other species: on the hunt, before the very throw, they climb to their hind limbs, and, with their heads raised high, begin to swing their tail.
Suborder Iguanoid
No other group of scaly can boast such a variety of life forms as iguanas. Like gecko-like, this suborder is not universally recognized. It has 10 families: collared iguanas, anolis, helmet lizards, chameleons, tenon-tailed iguanas and others. All iguanides are divided into two types of individuals, which differ in the characteristic shape and structure of the body. In wood-type iguanas, the body is compressed laterally, and in terrestrial iguanas, the body has a disk-shaped flattened shape.
The calling card of all iguanas is pleurodont teeth, which are attached to the inside of the jaws. The heads of individuals are covered with multiple irregularly shaped shields, and the back is covered with scales, which are transformed in places into horny spines, tubercles, and prongs.
Most iguanas are predators that feed on spiders, insects, and worms. Larger individuals have vertebrate prey, most often lizards.
Amphisbenes
Reptiles dvukhhodki (amphisbens) are very similar to lizards, so this suborder has long been recognized as their family. Unlike their cousins, amphisbens lead an underground life and resemble worms in appearance. They have 4 families: hirota, palearctic worm-shaped lizards, amphisbene and rhineurids.
Animals, which belong to the squamous order, have a typical common feature - horny scales on the body. Amphisbenes also have a worm-shaped body, covered with a solid horny film and entwined with transverse rings with intersecting grooves. Therefore, their appearance also resembles scales. The horn brushes that cover the head of most scaly, amphisbene perform burrowing function.
Amphisbens prefer to live in termite nests. Like moles, they dig moves in the ground and move easily along them. Interestingly, on the surface of the earth they move in straight vertical lines.
Life span
The squamous squad does not differ in special longevity. Experts agree that there is a direct relationship between life expectancy and animal size. Large individuals of lizards live 20-30 years, and small ones no more than two years or even less. Geckos spend their time up to 13-15 years, numbers can be more, depending on the size of the individual. Snakes in nature reach an average of 30-40 years, but in captivity, thanks to the departure of a person, the years are significantly increased. There are species, for example, pythons, their age can reach up to 100 years.
It should be noted that the life expectancy of reptiles is significantly reduced as a result of diseases, injuries and attacks of predators. But recently, there has been a tendency to keep exotic animals as pets and this, of course, adds to their years of life.
The value of the squamous squad
Like all living things on this earth, scaly reptiles have their purpose in nature and human life. They are active participants in the food chain, where dropping out or changing the abundance of one species will be a disaster for everyone else.
Lizards and snakes are of great benefit to people, destroying harmful insects and rodents, which not only harm crops, but are also carriers of dangerous infections. In addition, snakes are eaten by some peoples of the East. They believe that scaly meat and blood give the body longevity, youth, and health.
In medicine, the use of snake venom is also priceless, it is present in many medicines and ointments. And on top of that, the skins of these reptiles are used in the manufacture of accessories and shoes.
Poisonous representatives
A separate topic of discussion will be the toxicity of some representatives of the squamous squad. About one million people suffer from snakebites annually. And, despite the effectiveness of the treatment of modern medicine, mortality remains very high. A large number of attacks recorded in tropical and subtropical zones.
What animals of the squamous order are dangerous and pose a threat to human life? As a rule, these are separate species of snakes and the family of Toadjack lizards. Some still mistakenly identify iguanas as poisonous reptiles, but in fact, they have no toxic poisons. They transmit a large number of bacteria with a bite, which can cause inflammation. But in the suborders of amphisbene and geckos no toxic representatives were found.
In snakes, 5 out of 18 families are completely poisonous or contain poisonous species: the original, aspid, viper, pit, and rattlesnake. In Russia, a family of vipers is common. Cases of attacks are observed in Siberia, the Far East, the Middle Urals and the republics of Transcaucasia.
Interesting Scale Facts
- Legless lizards can easily be confused with snakes. But with a thorough examination, you can notice the head and ear canals that are not inherent in snakes.
- The gecko is mentioned in the Bible as anaka (Leviticus 11:30).
- Snakes can hibernate for three years without eating.
- In Mexico, iguana dishes are part of the national cuisine.
- Poisonous snakes love classical music and dance with pleasure to it.
- The copper-headed snake emits the smell of fresh cucumbers.
- In the Mayan tribe, the iguanas were revered, the house with them symbolized the house of the deity.
- The color of the chameleon depends on its emotional state, and not on the surrounding background.
- King cobra eats snakes, including poisonous ones. Also, unlike other species, she takes care of her offspring.