Bone claws, oxygen-absorbing “hair,” and hands-on frog dads. Meet the hairy frog (or wolverine frog), one of nature’s strangest amphibians.

Known as Doñana’s Firefighting Donkey Battalion, this unit is responsible for preventing wildfires in parts of Spain—all thanks to their seemingly bottomless appetites.

It was one of those wonderfully wet Finnish summer days — unexpected, slightly comic, and, in hindsight, perfect. I was on the Kuopio leg of a bike-and-train trip through the country, negotiating a ...