Reptiles are vertebrate animals of prehistoric origin that have inhabited the planet for 350 million years. They live on the land surface and in some aquatic ecosystems. They are the evolutionary descendants of dinosaurs.
Examples of reptiles are the common iguana, the chameleon, the caiman turtle, the cobra, the Komodo dragon, and the horned lizard.
Characteristics of Reptiles
The most common physical characteristics of reptiles are the following:
- Their skin is covered with scales.
- They have two holes on the top of the head, above the eyes.
- They are Tetrapods: they have four limbs, and if they don’t, they are evolutionary descendants of species that do.
- Their heart has three chambers, and they also have two aortic arteries.
- These are oviparous animals: embryos develop inside eggs that are hatched after they have been laid.
- They metabolize food slowly.
- They can regulate their body temperature to be exactly the same as their environment.
Reptile Species
There are more than 7,500 species of reptiles registered, but this number can vary depending on two factors.
- The discovery of new species.
- The extinction of existing species.
70% of the known species is made up of lizards and snakes. However, there are other registered species.
Currently, with the development of the field of genetics, the official classification of reptiles is a subject of debate. The classification shown below is the last official classification on which there was consensus (excluding amphibians). It was established according to the findings of Edward Tyson (1683).
| Reptile type | Example | Number of species |
| Lizards | Green Iguana | Over 4300 |
| Snakes | Rattlesnake | Over 6000 |
| Tuataras | Tuatara of the island Hermanos | 2 |
| Turtles | Galapagos | Approximately 356 |
| Crocodiles | Orinoco Cayman | 13 |
Size of Reptiles
Reptile sizes vary greatly. The Madagascar dwarf chameleon (Brookesia minima) is the smallest known reptile, measuring 30 millimeters on average. The Nile crocodile can be up to six meters long and the anaconda up to nine meters long.
Reptile diet
The staple diet of reptiles is based on animal protein, wild fruits and vegetables, but it varies depending on the species.
For example, the land tortoise is vegetarian, it eats flower petals, fresh leaves, carrots and strawberries. In contrast, the rattlesnake is carnivorous, feeding on small rodents, such as wild mice or bird eggs.
The water content that reptiles consume represents up to 2.7% of their body weight.
Habitat of Reptiles
They are distributed throughout the planet, except in Antarctica, and there is a greater abundance and variety of species in tropical and temperate zones. However, there are species, such as the dunes sagebrush lizard (Sceloporus arenicolus) in Namibia, that have developed the ability to survive in extreme climates.
99% of reptiles are adapted to terrestrial environments; however, they also live in lakes and swamps.
Only a few varieties have specialized to tolerate extreme environments such as brackish waters (in river deltas) or arid areas (deserts).
Reptile Reproduction
Reptiles are oviparous animals. They are characterized by sexual reproduction and the embryos develop inside eggs.
In general, they hatch from eggs that have been laid and incubated outside the mother. There are few species of reptiles that are ovoviviparous animals. That is, they evolved in such a way that newborns hatch from the egg while still inside the womb.
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