Reptilia Biology

Reptiles are descended from tetrapods or four legged creatures. With the exception of snakes, reptiles are still tetrapods. Reptiles are cold-blooded. Their bodies do not maintain a constant temperature. Their body temperatures depend on external sources of heat such as sunlight.

Most members of this class have a three heart with three chambers. They also possess lungs for breathing.  The skin of the Reptilia is covered by a watertight epidermis and sometimes protected by scales or scutes. The skin of some reptiles are used for camouflage to protect them. Other reptiles are able to lose and then regrow their tails. This is another defensive mechanism.

These animals are carnivores. However, some species like the turtles are herbivores. Most reptiles lay eggs.

Reptiles have eyes for vision. Some snakes also have specialized organs for detecting heat.


Reptiles belong to the phylum Chordata and class Reptilia. Chordates are animals that possess a notochord in their embryo stage of life. There are about 10,000 different species of reptiles.

Major reptile groups are the: Crocodilia (crocodiles and alligators); Sphenodontia (e.g. tuatara); Squamata (lizards and snakes); and Testudines (turtles and tortoises).


The Reptilia class can be found on every continent except Antarctica. They live in a wide variety of environments – ranging from tropical rainforest to desert ecosystems.

Reptilia and Humans

Reptiles are embedded in many human cultures. In Christianity, the snake tempts Adam and Eve. Reptiles are sometimes consumed for food or medicine. Some reptiles are perceived to be threats to human life because of their large size (e.g. crocodiles) or venomous nature (e.g. rattlesnake).

Improving Your Reading and Thinking Skills

Think for a few moments. Try to recall the major ideas in this article. When you are done, click the box below for a list of main ideas.


How did you do? With practice, you should be able to identify many of the major ideas. You may even discover some important ideas that aren’t listed.


Reptiles, National Geographic.


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9 comments on "Chordata Phylum: Class Reptilia"

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Ronand Abella

Ang mga butiki ay mga tatlong puso.Para kapag mamatay sila mabuhay sila.Pero kapag mainitan ng tubig init mamatay lahat puso niya.

Ronand Abella

All Reptiles are cold-blooded. The body’s of all Reptiles depend on the sunlight’s temperature.Some of the Reptiles have three hearts.There body’s is covered with watertight.

Webster Gabiana

Reptilia ay tawag-bloded nilalang.

Webster Gabiana

Reptilia are cold-bloded creatures.

Webster Gabiana

the animals are so wald ➡ 🙂 or 😡