Reptiles are a class of creatures consisting of snakes, tuataras, lizards, turtles and crocodiles. They’re tetrapods, but a couple species of lizard as well as the snakes have no limbs or their limbs are considerably reduced in size.
Their bones are ossified as well as their skeletons more powerful than those of amphibians. The teeth are conical and largely uniform in size. The surface cells of the epidermis are changed into horny scales which create a waterproof layer. Reptiles are not able to utilize their skin for respiration as do amphibians and have a more efficient respiratory system by enlarging their chest walls, drawing air in their lungs.
The heart resembles that of the amphibian however there’s a septum which fully separates the deoxygenated and oxygenated bloodstreams. The reproductive system was created with a copulatory organ present in many species, for internal fertilisation. The eggs are surrounded by amniotic membranes which grow in some species, or prevents them from drying out and are laid on land. The bladder is not large as nitrogenous waste is excreted as uric acid.