Why Do Frogs Go Through Metamorphosis?

The process where a tadpole turns into a frog is called metamorphosis and it is an amazing transformation almost every organ has to change so that the tadpole can go from living underwater to living on land as an adult frog. Emma asks biologist chris rossing why don't they just get born as tiny baby frogs and grow up like other animals do. What would you say the best part of your job is? The fact that i get to work with endangered amphibians when you release them into the wild  that might be important out of those otherwise they might not be alive.