Do frogs breathe through their skin?
Cutaneous respiration
The skin of amphibians is a major site of respiration in all species for which measurements are available.[1] Cutaneous respiration is the sole respiratory mode of lungless salamanders (family Plethodontidae) which lack lungs entirely yet constitute the largest family of salamanders. Cutaneous respiration in frogs and other amphibians may be the primary respiratory mode during colder temperatures.[2]
Cutaneous respiration
Mammals are endotherms, ("warm-blooded") and have higher metabolic demands than ectothermic ("cold-blooded") vertebrates, and the skin is thicker and more impermeable than other vertebrates, which preclude the skin as a major source of gas exchange. However, small amounts of respiration may occur, and in bats, the highly vascularized wings may account for up to 12 percent of carbon dioxide excretion.[3] In humans and most other mammals, cutaneous respiration accounts for only 1 to 2 percent.[3][1]