Ugly amphibians with bodies built for water and soil

Amphibians exchange water and gases through permeable surfaces, so skin is central to how they live. The folds of the Titicaca water frog increase available surface area, while the axolotl keeps external gills and other juvenile traits throughout adult life.

Other species are shaped by concealment. The purple frog has a compact body and pointed snout for burrowing. The black rain frog has short, strong limbs and a round body that work underground better than they would in a long jump.

Unusual amphibians are also conservation reminders. Restricted ranges, freshwater pollution, introduced predators, harvesting and habitat change can affect species whose entire wild distribution fits within one lake system or mountain region.