Reptiles-General Characteristics

Reptiles encompass over 6500 species. This article will discuss their common attributes.

The reptile is an ancient breed, dating back to the Carboniferous period of geological time. 330 million years ago, the reptile developed the ability to lay an amniote egg, making them the first animals with the ability to live and multiply on land, opening an entirely new environment for colonization. Reptiles continued to grow and multiply and eventually dominated the Earth for over 200 million years.

Today, however, only a few orders of reptiles remain. The four remaining orders are turtles, Chelonia, lizards and snakes, Squamata-tuatara-Rhynchocephalia, and the crocodiles, Crocodilia. These four orders are then subdivided into several subclasses which are based on the anatomy of their skulls. The 5 subclasses are determined by the openings in the skull and where they are located, and how many exist. Today's reptiles fall into only 2 of the 5 subclasses and science has determined that many more forms of reptile existed in prehistoric times that we may never discover. There are over 6,500 species of living reptiles on the Earth today. Most of the lizards on the Earth today are smaller than their predecessors, with the exception of crocodiles, which can grow as long as 30 feet, as well as some species of snakes that grow up to 30 feet, a few giant tortoises that grow up to 6 feet and the giant komodo dragon which can grow as big as 11 feet.

Reptiles are cold-blooded, scaly skinned vertebrates. Their hearts have three or four chambers, and, like humans, they breathe through lungs. They breathe through their lungs throughout their life, unlike the amphibian, who begins life breathing through gills which may later develop into lungs. This is one of the major differences in reptiles and amphibians. Most reptiles, are considered to be tetrapods, or 4 legged animals. Though snakes are the exception to this, it is believed that the snake evolved from a reptile who had four legs. Being heterothermal, or cold blooded, a reptile must adjust its body temperature to its environment The body of a reptile works optimally when it can get the right amount of heat from its surroundings. That is why you will often see reptiles lying on a rock, basking in the sun. Different reptiles thrive in different environments. Some reptiles prefer cool weather and will thrive in temperatures as cold as fifty degrees, while others prefer a warm climate, having temperatures up to 104 degrees Fahrenheit. When the temperature is not conducive to a reptile, they can go into a state of hibernation and wait until the weather is right for them to be active. Even during their active times they have to vary their periods of exposure seeking the cool of shade or underground to conserve energy. A reptiles scaly skin absorbs heat from the sun and prevents animals from drying out. As a reptile grows, it sheds its outer layer of skin. A reptile has the same jaw articulation as a bird, but differ from amphibians by the way their skull attaches to their back bones. The reptile is a fascinating creature with roots reaching all the way back to the age of the dinosaur. By studying these creatures, we can gain insight on the lives of those animals living so long ago.

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