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.
Spotted grass frog
The male and female frogs can be sexed by the presence of a flap of skin around the thumbs of the females. This is used to froth the water during amplexus to create the floating foamy nest that it lays eggs in, which is roughly the size of a human palm. The tadpoles of this frog are comparatively large (up to 6 cm). This frog spends a minimum of 3 months in the tadpole stage.