Tree frogs reduce surface area by selecting a shaded site and tucking limbs close to the body. Some amphibians dig deep burrows and stay there for up to nine months at a time. Terrestrial amphibians are generally nocturnal, with the exception of some species of anurans. The skin of amphibians is highly permeable. Most salamanders and all frogs that live in aquatic areas have smooth skin on the belly and sides.
Most terrestrial anurans have rough skin on the belly and the thighs.
The rough stomach surfaces provide a great surface for water absorption. For example, sometimes, the amphibian may not want water to enter the body. For such occasions, some amphibians have developed ways of waterproofing the skin. They form a cocoon that encases the body. They make these cocoons during long periods of dormancy and during the day.