1. Fish has several gills Fish has four gills. Its gill cover has two pieces. After lifting it, you can see the fish gills inside, which are its respiratory organs. When the water flows in from the mouth, it will flow out from the gills. Because the direction of the water flow is opposite to the direction of blood flowing in the gills, it can efficiently absorb oxygen from the water and discharge carbon dioxide at the same time.
Second, what auxiliary respiratory organs do fish have1, swim bladder: For teleost fish, swim bladder is an important organ to change body density, which can make it float or dive in water. But for some special fish, such as African lungfish, swim bladder is an auxiliary respiratory organ. When the river enters the dry season, the fish will be exposed to the air, and this time it needs to breathe with the swim bladder.
2. Skin: A mudskipper is a kind of fish that can survive after leaving water, relying on the breathing ability of skin. This kind of fish usually lives in shallow water along the coast, and will stay on the tidal flat after the ebb tide, which is convenient for it to forage, and can even jump and move with the help of chest muscle handle.
3. Intestine: Misgurnus anguillicaudatus living in mud is also a kind of fish. It can swallow air on the water when the water is deprived of oxygen, because its intestine can breathe. In addition, after the pool dries up, it can drill into wet mud, so long as the body surface is kept moist, it will not die.
