Characeristics
- They are coldblooded
- The skin has a few cutaneous glands and high levels of keratin. This helps to prevent water loss through the skin.
- The scales and scutes are formed from the epidermis and are also made of keratin, to protect the body.
- Reptiles are considered as tetra pods with two sets of paired limbs. Most of these animals have five clawed toes on each limb.
- All reptiles have spinal columns and a strong skeletal system with a rib cage. They have a well-developed brain and a central nervous system.
- Unlike amphibians, reptiles do not pass through an embryonic stage with gills. These animals breath with well-developed lungs, right from birth. Most of them have two lungs, except some snakes.
- All reptiles have three-chambered hearts, except crocodiles, which have four-chambered hearts (2 atria, 2 ventricles), like mammals and birds.
- Reptiles have a digestive system which has a muscular opening at the base of the tail.
- In case of reptiles inhabiting arid regions, water is further absorbed into the body and only the remaining waste is excreted.
- Twelve pairs of cranial nerve.
- These amniotic eggs can survive without water, as they have protective shells and membranes that allow oxygen and other gases to enter.
- Respiration by lungs only.
- The offspring of reptiles resemble the adults at the time of birth itself. There is no metamorphosis, as in the case of amphibians.
- Lateral sense organs are absent.
- They are the first animals with amniotic eggs, that can be laid on land and not in water.
Evolutionary Origin
References:
Characteristics of Class Reptilia. (n.d.). Retrieved June 3, 2015, from http://www.preservearticles.com/2011082011053/characteristics-of-class-reptilia.html
Characteristics of Class Reptilia. (n.d.). Retrieved June 3, 2015, from http://www.preservearticles.com/2011082011053/characteristics-of-class-reptilia.html