Different Types of Reptiles: Definition, Images, and More

 Reptile is first and foremost an evolutionary classification. This class of animals all have a common ancestor that existed more than 300 million years ago. However, it also has a few traits in common. Fundamentally, all reptiles have four legs or are related to animals that have four legs (including snakes, which still apparently carry some of the genes for making legs). Like other vertebrates, they have a backbone that protects the spinal cord. The majority of reptiles also have the following traits in common:

Rough scales - Reptile skin is coated with bony plates, rough horny layers of scales, or both. Keratin, the same material that makes up nails, hair, and claws, makes up these scales. The lack of a mammalian-like dermal layer causes the skin to be thinner than you may think. However, the water-tight skin of the reptile does enable it to survive and flourish in drier habitats.

Regular shedding - Throughout their whole lives, reptiles regularly lose their skin. Because the skin doesn't truly develop in proportion to the body throughout the teenage stage, shedding tends to occur more often at this time. Once the reptile reaches adulthood, the frequency of the shedding begins to diminish.

Egg-laying - All reptiles are oviparous, meaning they lay eggs in a nest, with the exception of certain snakes and lizards, which give birth to live offspring. The young are either born male or female depending on the soil temperature at this time. Although it is extremely uncommon, some lizards and snakes have been reported to reproduce asexually.

All reptiles rely on their highly developed lungs to breathe air. Even creatures having skin that is permeable and other adaptations can never fully exhale without using their lungs.

With a few notable exceptions, reptiles have generally small digestive systems and consume meat. They can afford to eat fewer meals and digest food more slowly because of their sluggish metabolism.

Chemoreception: Some reptiles, but not all, have chemically sensitive organs on the roof of the mouth or the nose that can be used to detect prey. The sense of smell may be replaced or supplemented by this skill. Snakes in particular flick out their tongues quickly to detect substances in the air.

Skull morphology: The skull of a reptile differs from those of other animal groups in a number of ways. They have a very powerful jaw, a single auditory bone called the stapes that transfers vibrations from the eardrum to the inner ear, and a single bone where the skull joins to the first vertebrate.