African lungfish is a special kind of fish, which can breathe through gills when in water, but it has a special swim bladder, which allows lungfish to breathe air directly after leaving water. In the dry season in Africa, lungfish will get into the wet mud and make a small cave to curl up; In order to prevent dryness, it will secrete special mucus from the skin to wrap the whole body, forming a waterproof layer, leaving only a small hole to breathe, relying on its own muscles and fat as nutrition, and its metabolic rate will be reduced to one-sixtieth of the original, about 2% less than normal.