It is a larva when it is first born and it is like a tadpole. It has a tail and gills but no lungs. It is a lot like a fish. When a larva turns into an adult, their body and breathing structures changes. The tail disappears, legs form and their mouth gets bigger.
Lungs replace gills and other organs.
I learned this information from the inter net. The first day I started this project I thought it would be easy. It didn't turn out that way. Instead I changed it to frogs. I think I made a good choice.