andrew lansens

There are countless species and varieties of reptiles around the world. Even though there are many differences, reptiles do share a few common traits.

For starters, they use lungs to breathe. Lizards might breathe using the same muscles they use to run and crocodiles have a more flexible diaphragm, but overall, reptiles have lungs that are more advanced than amphibians, but not as refined as mammals. Reptiles also have scales made of keratin protein. Scales provide protection from predators, help retain water, and can play a role in courtship and territorial clashes. Reptiles are not the only animals to have scales, but it is a common characteristic among all reptiles.

Another characteristic is that they're all four-legged vertebrates (or descended from four-limbed animals, like snakes). This is another shared trait with other types of animals, which indicates that reptiles are an evolutionary middle ground of sorts between amphibians and mammals. For the most part, female reptiles lay eggs but it's not exclusive to all reptiles. There are some species that develop their young inside their bodies and give birth to live young, like the Viviparous Lizard and the Adder.

Reptiles are known for their cold-blooded metabolisms. If you've ever seen a reptile in an enclosure, you might have noticed lamps and other forms of heat. That's because basking in heat increases their internal body temperature to give them the energy they need for daily activity.

What are the different types of reptiles?
Reptiles can be classified into four major groups:

Crocodilia
Which has 23 different species of Alligators, Caimans, Gharials, and Crocodiles.

As you may know, the Crocodilia are large, semiaquatic and predatory animals. They're commonly found in the lowlands of the tropics and usually have long, flattened snouts and canonical, peg-like teeth. Certain species of crocodilian are traded as exotic pets when they're young but are often abandoned as they grow larger and more dangerous.

Squamata
Which are lizards and snakes, and have almost 8,000 species.

These reptiles vary in size (from a dwarf gecko that's less than an inch long to an anaconda which can reach over 17 feet). Their ability to move their quadrate bones is what helps them open their mouths wide enough to consume larger prey.