Gas exchange in some animals, they may rely on an Exchange to the surface only for the trunk, and there are also some animals are able to exchange the gas breather is trimodal both skin, lungs and gums.
Gas exchange in animals, some of them may require the exchange of body surface alone. And, there are some animals that are trimodal breather is to exchange gases with the skin, gills and lungs.
Gas exchange in some animals, they may have lived through trade body skin only. And there are also some animals that are trimodal breather is able to gas exchange, both skin, gill and lung.