Reptiles – Concept, types, reproduction and characteristics

We explain what reptiles are, their characteristics and the types of reptiles that exist. How is its reproduction and digestive system.

Reptiles - Blue Snake
Reptiles have a presence that is both fascinating and frightening.

What are reptiles?

We call reptiles to a group of quadruped and vertebrate animals, cold-blooded, whose main characteristic is having a skin covered with keratin scales. They are very abundant animals, especially in warm habitats, whose name comes from their way of walking: it comes from the Latin reptile, “That creeps.”

The reptiles appeared on Earth 318 million years ago and they were the predominant way of life during the Mesozoic (Triassic, Jurassic, Cretaceous), in the so-called “Age of the dinosaurs”. They are evolutionarily related to amphibians and birds; and some prehistoric reptilian species gave rise to the first mammals.

In human cultures, reptiles they have a presence that is both fascinating and frightening, given its dry, ancient appearance, and its ferocity in the case of large predators such as crocodiles, alligators and snakes. Many have been associated with sinister powers or with demonic entities, as is the famous case of the serpent in the Garden of Eden narrated in the Bible.

Characteristics of reptiles

Reptiles - turtles
Some reptiles have a rigid shell that is integrated into the skeleton.

Reptiles, broadly speaking, have adapted to terrestrial life, although many species have subsequently returned to aquatic environments to prey. This means that they have pulmonary respiration, with a double circulatory system and a series of adaptations that allow them to conserve water as much as possible. Their scaly skin is tough and rough, allowing them to warm the body by exposing it to the sun, as reptiles cannot internally regulate body temperature.

Their bodies generally they are quadruped, although some species have lost their legs, like snakes, and others have a rigid shell integrated into the skeleton (like turtles). They generally have a good sense of smell and in the case of snakes a sense of touch that allows them to perceive vibrations from the ground.

Types of reptiles

Reptiles - crocodile
Crocodiles are terrestrial but with aquatic eating habits.

There are four large groups of reptiles:

  • Turtles (testudines). Adapted to aquatic and / or terrestrial habitats, they have a rigid shell that is born from the endoskeleton itself and protects the animal’s torso. They have a horny beak in the mouth and a small tail, as well as four legs.
  • Scaled lizards (squamata). Like lizards and snakes, they may or may not have legs, respectively, and have long bodies covered in thick, rough scales, which provide protection and prevent desiccation of the body.
  • Alligators and crocodiles (crocodylia). Terrestrial but with aquatic eating habits, they are some of the fiercest reptilian predators on the African and American continents, thanks to their huge toothed jaw and robust muscular bodies.
  • Tuátaras (rhynchocephalia). A group of living fossils that today includes a single genus, Sphenodon, of three species, endemic to New Zealand. They are reptiles of about 70cm in length and evolutionarily very close to dinosaurs.

Reproduction of reptiles

Reproduction of reptiles is sexual, that is, it involves the internal fertilization of the female by the male during copulation, as well as the exchange of gametes (sex cells). Later, the female lays eggs, usually in a nest that she fiercely guards, or buried near water (like turtles). The young emerge from them, identical to their parents but smaller, without the need for metamorphosis of any kind.

Digestive system of reptiles

Reptiles - Iguana
There are herbivorous reptiles that swallow stones with which to grind eaten food.

Reptiles have a simple and short digestive system, which is adapted for the decomposition of meat, since they are mostly predators. Your digestion it is however much slower than in mammals, in part because they are unable to chew food and must swallow it in large pieces (or whole in the case of boas), so it is usual to see them sleep or rest after feeding.

Too there are herbivorous reptilesOf course, in the absence of the possibility of chewing, they swallow stones with which to grind the eaten food, just as birds do. In addition, these rocks serve as ballast for marine species, facilitating immersion.

The dinosaurs

Reptiles - Dinosaurs.  velociraptorimage-13422″ height=”412″ src=”” width=”800″ />
The name “dinosaurs” means “terrible lizards” in Latin.

During the Mesozoic Era, some 251 million years ago, reptiles dominated the earth and were the dominant group, acquiring enormous size and diversification never seen before (or since). These large reptiles existed for almost 200 million years until they became extinct in the transition from the Cretaceous period to the Cenozoic Era, 65 million years ago, for reasons that are unknown, but whose evidence points to a global catastrophe. Of these creatures only fossil records remained, which upon being discovered by humanity received the name of dinosaurs, that is, “terrible lizards” in Latin.

Reptiles in danger of extinction

Reptiles - Dwarf Chameleon
The dwarf chameleon is native to South Africa.

Many reptilian species are today at risk of disappearing due to human action. Among them, the following stand out:

  • Dwarf chameleonBradypodiontaeniabronchum). Tiny version of ordinary chameleons, native to South Africa.
  • Ricord’s iguana (CycluraRicordi). Endemic to the island of Hispaniola, in the Caribbean, few populations remain to the southwest of the Dominican Republic.
  • Giant lizard of La Palma (Gallotiaauaritae). Endemic to the Canary Islands, it has been becoming extinct since humans colonized the island of La Palma, due to the introduction of cats, agriculture and their indiscriminate hunting.
  • Orinoco Cayman (Crocodylusintermedius). It is the largest predator in Latin America, endemic to the Orinoco River region in Venezuela. It has a maximum length of 7 meters and is in critical danger of extinction.
  • Hawksbill turtle (Eretmochelysimbricata). It is a species of marine turtle with a mottled body and whose meat and shells are highly coveted, which is why they have been hunted to practically extinction.
  • Chinese crocodile (Alligatorsinensis). Endemic to the mouths of the Yangtze River in China, it is dark green to black in color, and lives for about 40 years.

Examples of reptiles

Lizard - reptiles
Lizards can often be seen climbing the walls of American homes.

A perfect example of reptiles are the water turtles that many had as children as pets (Trachemysscripta), as well as common iguanas (Iguana iguana) that in many tropical countries can be seen wandering the countryside or even some cities. Also the Iranian crocodiles (Crocodyluspalustris) of zoos, the green anacondas of the Amazon (Eunectesmurinus) or house lizards or geckos (Hemidactylusmabouia) that we can find by climbing the walls of American homes.