Some general features of the crawling animals or reptiles are: These organisms that belong to the class of Reptilia are all vertebrates. This means all of these animals possess a backbone. Not all reptiles produce eggs. While there are some reptiles that tend to lay their eggs with hard shells on the land, there are others who give birth naturally to their young generations. All reptiles have certain small scales as well as hard plates that are created using the protein keratin. There are scutes present in some reptiles. The armour found in crocodiles and the shell of the tortoise is made up of this component. Scutes have a similar appearance to the scales that are found in snakes and certain species of lizards.These animals are cold-blooded and ectothermic.