There are more than 4,000 known species of frogs, including toads. The distribution of frogs ranges from tropic to subarctic regions, but most species are found in tropical rainforests. The life cycle of a frog starts with an egg, еggs hatch and continue life as tadpoles, аt the end they transition into adult form. Compared with the other two groups of amphibians, (salamanders and caecilians), frogs are unusual because they lack tails as adults and their legs are more suited to jumping than walking. The physiology of frogs is generally like that of other amphibians because oxygen can pass through their highly permeable skin. They range in size and come in a rainbow of colors and patterns. The African Giant is the largest, it can grow to 26 inches long. African clawed can live 15 years, Bullfrogs can live 30 years. The earliest known frog appeared about 190 million years ago.