Cutaneous respiration
The skin of amphibians is a major site of respiration in all species for which measurements are available. 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.
Orbiting Frog Otolith
Both flight frogs had electrocardiogram (ECG) electrodes implanted in their thoracic cavities and microelectrodes implanted in their vestibular nerves. The frogs were demotorized by cutting their limb nerves to prevent them from dislodging their implanted electrodes, and to reduce their metabolic rates. With this lowered metabolic activity, the frogs could survive in good health without being fed for as long as one month. Immersion in water allowed the frogs to breathe through their skin. The water medium also helped to move carbon dioxide and heat away from the animals.