We talk all the time about amphibians breathing through their skin, and continually evolving. So it’s not completely a shocker that in Borneo scientists have found the first frog species that is lungless. It’s the Barbourula kalimantanensis. Here’s the article.
So how did this happen? Here’s excerpt from ITWire:
Scientists currently are leaning toward that theory that the frog once had lungs long time ago but had difficulties going from the surface to the bottom of fast-moving water in cold streams because of the buoyancy of air-filled lungs.
Thus, the frogs slowly evolved from breathing through lungs to breathing through their skin, and eliminated the presence of lungs in their bodies.
Scientists already know that amphibians rarely breathe through their skin because it is more difficult to get sufficient oxygen into their bodies than with the process of breathing through lungs.
Only cold-blooded animals breathe through their skins because they don’t move as much, so do not expend as much oxygen.
The scientific community knows of only one family of salamanders and one species of caecilians that are lungless amphibians, besides B. kalimantanensis.
For the lungless frog whose habitat includes cold water, the low temperatures of its water holds more oxygen than warm waters, which is desirable. Plus, rapidly flowing streams allow more oxygen to flow over the body of the lungless frogs than slowly moving streams, which is also beneficial for the frogs.
So, with its habitat being clear, cold, fast-flowing streams, the lungless frogs are very happy living in such streams in Borneo.