Evolution is defined as the change in the hereditary characteristics of populations over generations (Caroll, 2009). The environment is constantly changing, so organisms must change to resist changes in the environment in order to survive and reproduce (Caroll, 2009). Regular changes in the genetic material of organisms over generations can lead to the development of new species more adapted to the environment (Caroll, 2009). It is said that evolutionary failure can lead to the extinction of a species (Caroll, 2009). This essay deals with the evolution of amphibians. Amphibians are classified into three orders (anura, caudata and apoda) and belong to the superclass tetrapods (Kolesova et al, 2007). Apoda are made up of legless organisms, and these organisms normally live in mounds. Tretrapods are composed of four-limbed vertebrates; and examples of tetrapods are reptiles and amphibians (Kolesova et al, 2007). Tetrapods were the first vertebrates to be able to walk on land, during the Devonian period, approximately 360 to 370 million years ago (Kolesova et al, 2007). Before the existence of amphibians, almost all vertebrates lived in water (Kolesova et al, 2007). Amphibians are animals adapted to live on land and in aquatic habitats (Kolesova et al, 2007). Young amphibians spend their youth in the water, breathing through their gills; as they grow, they tend to lose their gills and develop lungs which allow them to adapt to life on land since they breathe air (Kolesova, et al, 2007). There are a number of amphibians like salamanders that do not have an aquatic stage in their life, they are completely terrestrial (Kolesova, et al, 2007). Some amphibians do not... middle of paper ....... An example of an amphibian well adapted to life on land is the order (Anura) and family (Ranidae) true frogs. These structural features include changes in the inner ear. The inner ear was made up of papillae and double transmission channels which made it possible to detect airborne sounds. The reasons for the changes in the ears were due to the fact that the air is 1000 times less dense. The eyes had specialized visual cells in the retina to allow these amphibians to easily catch their prey. They also have stronger spines and muscles. The skin with glands helped with cutaneous respiration and the production of toxins. Toxic secretions from the glands serve as a defense mechanism. The stalked teeth allowed them to adapt to a new diet outside of water. The evolution of amphibians led to the evolution of many vertebrate animals seen today.