Reptiles. Vertebrates. animal Kingdom. Wildlife. Fauna. Zoology.

They are very primitive reptiles that have remained unchanged for more than 200 million years, whose main characteristic is that they have a bone shell that covers almost the entire body, in the form of a box, with a top or back and a lower part or bib.
The limbs are short and leave the shell laterally.
They can be hidden inside almost completely, the jaws are beak-shaped, without teeth and with sharp edges.
They feed on plants and / or animals.
They all breathe through lungs.
There are terrestrial, freshwater and marine species. Depending on their type of life, the different forms of legs in the turtles can be distinguished according to whether they are aquatic or marine terrestrial, the latter have the legs transformed into fins.

Some species of chelonians or turtles:

• Greek turtle or common turtle.
• Snapping turtle
• Common European Galapagos

They are reptiles that live exclusively in tropical areas.
Its shape is elongated; They do not make molts, so their skin has a very thick corneal layer, which is increasing throughout its life.
They have an elongated snout with conical and sharp teeth, located on the edge of the jaws, which they use to catch and kill their prey.
The nostrils are located at the end of the snout and close them during the dive.
The eye of the crocodile is protected by a third transparent eyelid.
Its trunk is robust and the powerful tail, which is the main swimming organ.
Their legs are short and they crawl on the ground.

They are aquatic habits and live in groups.
They are oviparous and the young are born very developed.
They are classified as: crocodiles, alligators or alligators and gavials.

There are 16 species of crocodiles, which inhabit almost all of them in Africa, with representatives on other continents except in Europe. The best known is the Nile crocodile.

Gavials are distinguished by their long and narrow jaws armed with numerous teeth. They are essentially aquatic and are peaceful animals that do not attack man.

Alligators or alligators live in the rivers and swamps of America, except the alligator of China.
They can reach 5 meters and live forming large groups. He almost never attacks the man. The best known are the alligator of the Mississippi, the black alligator, the alligator glasses and the yacaré.

They are reptiles with a cylindrical and elongated body, without limbs.
 They move crawling with undulating movements of their muscular body.
They have skin covered with scales that change periodically.
Eyes with transparent eyelids soldiers. They have no eardrum.
The mouth is very dilatable and allows them to swallow their prey whole. The tongue is bifida and mobile, which they use as sensory organs of smell and touch.
Its skeleton has many vertebrae: the vipers have 200 and the pythons, 400.
Some have hollow teeth with which they can inject poison.
There are about 2,700 species.
Non-poisonous families are: snakes and boas or constrictors.
The poisonous are the cobras, viboras and marine snakes.

• The boidies or constrictor snakes, as well as the snakes or collubrids are not poisonous (except the bastard snake).
  The constrictors hunt and kill their victims by strangulation, winding over them with their powerful rings.
  Among them the best known are the boas, the pythons and the anaconda.
  Some of these reach 7 meters in length.
• The hydrophilic or sea snakes are very poisonous. They have a flattened tail, which serves as a swimming organ.
  They live near the shores of the Indian and Pacific oceans.
  These snakes are viviparous, that is, the young are born already formed.
• Vipérides or vipers have poisonous teeth.
  The viperinos or vipers themselves are terrestrial snakes that live in the ancient continent, among which are the asper viper, the European viper, the horned viper, the Rusell viper, etc.
• Crotalinos are almost all Americans and have facial pits, which are heat-sensitive organs, with which they locate their victims.
  You can quote rattlesnakes, moccasin, etc.
• The elpids or cobras are poisonous snakes that are characterized by having on both sides of the head a kind of hood that can spread at will over the ear when irritated.
  They almost always live near water courses and live in Africa and Asia.
  The African black mamba and coral snakes that live in the Americas are also ellipid.

There are about 2,000 species of saurus distributed in about 20 families.
The morphological features are: skin covered with scales and small corneal plates; elongated body and long tail; eyes with mobile eyelids and five fingers with nails on each leg.
They are distributed all over the world, except in cold areas.
The different families of saurios are: gecónidos, iguánidos, chamaleónidos, lacértidos, varánidos, scíndidos and agánidos.

• The Geconids:
  They are all salamanquesas or geckos.
   They are crepuscular or nocturnal animals and have suckers on their fingers that allow them to climb walls, window panes, and even ceilings. They feed exclusively of insects. They spend the day resting in the sun and do not totally hibernate in cold weather, staying still without eating.
  Common salamanquesa.
  The fingers of the salamanquesa are provided with lamellae that form adhesive suckers.
• The iguanids
  There are about 300 species of iguanas and other genera with a variety of forms distributed in America, equatorial and tropical islands, Madagascar, Fiji and Tonga.  The great green iguana of the Antilles is 1 meter long. The anolis changes color like the chameleon. There are iguanas from the Galapagos Islands among which the marine iguana is counted.
  The basilisk runs leaning on the hind legs at a speed of about 12 km per hour. The fingers of the hind legs have broad lobes that increase the support surface and can even run on water.
• The chameleons or chameleons
  The fingers of the extremities are arranged in the form of a pincer, with which it is attached to the branches, aided by a prehensile tail. The eyes are located on balloons as ball joints and can move in all directions and with complete independence.
  Its tongue is retractable, of great length, with which they catch insects from which they feed.
  They have the power to change color by adapting to the environment around them.
• The eels are the crystal snakes or luciones.
  They are saurus with very small or totally absent members.
  They have a very fragile tail that can be detached at will.
• The lacértids are the lizards themselves and typical representatives of the Order of the Saurus.
  They have retractable bifid tongue, well developed limbs, long tail, eyes with eyelids and generally carnivorous diet.
  Among its species is lizards and lizards.
  The tepids are American lizards among which is the one meter long teal and that usually attacks poultry.
• The Varánids
  This family has about 27 species worldwide (none in Aragon), among which It includes the greater saurus that exists, the Komodo dragon.
  They inhabit the subtropical regions of Asia, Africa and Australia.
  They have a broad head, thick neck and long and solid trunk.
  The tail is long and sturdy with which they can hit hard.
• The helodermids
  There are only two species that live in North America and Mexico.
  They feed on invertebrates and small vertebrates.
  They have a solid body with tuber-covered skin.
  They are the only poisonous saurus, whose bite can be dangerous for man.
• The Spirits
  They are saurios that look like lizards that live in warm regions.
  They have very small limbs, and in some they are absent.
  His body is coated with very smooth and shiny scales.
  They are the scincos or skinks.
• The agamids
  They are considered the iguanas of the Old World.
  They live in the tropical and subtropical regions of Africa, Asia and Oceania.
  The family includes the common agama, the moloch, the hadrosaur, the flying dragon, which has developed some membranes on the sides that allow it to make planned flights, and King's clamidosaurus, which has a skin-shaped collar extension that extends when the animal feels threatened.