小朋友,不知道你有没有留心观察过,如果把很多泥鳅放在一只水桶里,它们就会在水桶里上下不停地翻动,同时还会吐出很多的泡泡。你知道这是为什么吗?原来,泥鳅的身体又扁又长,平常,它和其他鱼类一样,都是用鳃来呼吸的。但是,当水中缺氧时,泥鳅单单靠鳃呼吸,就满足不了生存的需要。每当此时,泥 Children, do not know if you have carefully observed that if you put a lot of loach in a bucket, they will flip up and down in the bucket, but also spit out a lot of bubbles. Do you know why? Originally, loach’s body is flat and long, usually, it is the same with other fish, are gills to breathe. However, when the water is lack of oxygen, the loach just breathe through the gills, it can not meet the needs of survival. Whenever this time, mud