ALL accounts of the metamorphosis of the common frog leave it to be tacitly inferred that when the front legs make their way through the operculum branchial respiration ceases, and that ...

After some time, the hind legs of the tadpole will begin to form. From them, they elongate and become fully formed limbs.

Soon they'll be tiny black tadpoles swimming in the water, breathing through gills on each side of the head. They're still growing and changing. Back legs grow first, then front legs. No need for ...