by skin
Cutaneous respiration.
Its not impossible. Many animals such as the earthworm and frog do it.
Respiration of animals in the Phylum Vertebrata, Class Amphibia, including classes such as urodela, anurans, & apodans. It involves respiration through the skin.
Amphibians
Frogs have cutaneous type of respiration i.e respiration through skin.Some species have lungs,but very rare in occurence.To know practically,take a frog and cover it completely by a blotting paper.After some time the frog dies
the gas that is used is oxygen
Frogs have multiple ways to breathe. While underwater, the frog's skin grabs oxygen directly from the water. While it's on land, it uses its lungs, but unlike humans, who use the diaphragm muscle to pull air in, the frog has to puff out its throat to get the air in. This is what causes the iconic frog ribbit.
The same as with any animal (or human) - respiration.
A frog's skin helps to regulate its body temperature through respiration and moisture absorption. It also acts as a protective barrier against predators and helps with camouflage. Additionally, the skin secretes mucus that keeps it moist and helps with respiration.
The organ that is part of the frog's respiratory system that is not found in the human respiratory system is the skin. The skin is not involved in human respiration.
An internal nare in a frog is a passage in the oral cavity that connects the mouth to the nostrils. It plays a role in respiration by allowing the frog to breathe while keeping its mouth closed, such as when submerged in water.
Moist skin helps in respiration. A think film of water is formed on the surface of frog, into which the atmospheric O2 gets dissolved and ultimately diffuses into the blood vessels underlying the skin. This is the reason, the skin of frog is richly vascular.