This stage occurs very quickly as this is the stage when the animal is most vulnerable to predation. Caecilians legless, burrowing or aquatic amphibians not many species and most are poorly known eyes are covered with skin or bone, but they are still sensitive to light a pair of tentacles between the eye and nostrils that are probably for chemoreception. Developing embryos eventually exhaust the yolk and get additional nutrients from the mother before birth. The fetuses bite or scrape the uterine wall, which cause a milky substance to be secreted. The fetuses eat this milk along with some tissue from the lining of the oviduct.
Gas exchange is via the gills of the fetus being pressed up to the uterine wall.
The skin of all amphibians is highly permeable to water and gases. For example, the skin is covered with mucus glands to aid in keeping the skin moist and in dehydrating conditions, an anuran will position its body to reduce the surface area that is exposed to the atmosphere. If an amphibian loses water, it can gain the water back once it is water. Many anurans have a pelvic patch , which is an area on the underside of the body that is highly vascularized for the uptake of water. An anuran can rehydrate by just having its belly in the water or on a wet substrate.