We have a tiny dark brown frog in P's best vase, along with 3 tadpoles who
are yet to develop more than 2 limp back legs. Had a mild panic that maybe
the frog would drown (not trusting the amphi part of amphibian, clearly) but
wikipedia to the rescue. Ton of extra fascinating information about frogs
of course:

– No real difference between frogs and toads, toads tend to have thicker
skin and are less dependent on water but not very consistent
– They have lungs but no diaphragm, so they have to swallow the air down
– Underwater they absorb oxygen throught their skin, they don't have
gills. But makes them susceptible to environmental poisons
– Their hearts have just 3 chambers – but then so do all 4 legged
vertebrates, other than mammals, birds and crocodiles

The tail doesn't fall off; it's weird, it just kind of shrinks. And once
the front legs have developed, suddenly the tadpole's back legs start to
work!