The diagram illustrates the stages of the life cycle of a frog.
Overall, the frogs experienced seven levels of evolution. The first four stages happened inside th water, while the others occur on land.
To begin with, the life cycle of a frog starts with eggs which is layed by adult frogs turning into an embryo. Next level, this embryo transforms into a tadpole which grows and is forms slightly. After that, front legs of frog start to grow which is the final stage underwater and pulmonary breathing starts on frog. In this level, the length of frogs tail also grows, which will shorten on the next level – becoming a tadpole frog. Finally, after all the stages complete, the tadpole frog turns into an adult frog and cycle continues.