在盛夏的黎明;在闷热的阴天;在水生植物密铺的水面;在油类所污染的水体,我们常常会看见鱼类将头抬起在水面,不停地将水和空气混合吞进。这种现象,人们称为是“鱼浮头”。 “鱼浮头”是由于水中溶氧明显缺少,鱼类感到体内严重缺氧,而被迫采取的一种保护性呼吸状态。这种持久保持的头向上、稳定身体的被迫性体位,十分耗费体力。同时,还停止了摄食。为努力保持这种体位和加速呼吸运动时,也就加速了体内氧气的消耗。它们 Dawn in midsummer; on the hot, cloudy days; on the water surface of aquatic plants; in the polluted water of the oil we often see the fish lifted their heads in the water, constantly mixing in the water and the air . This phenomenon, people call it “fish floating head.” “Floating fish” is a protective breathing state forced to take because of the apparent lack of dissolved oxygen in the water and the fish’s severe hypoxia in the body. This long-lasting head-up, steady body of the forced position, very physical exertion. At the same time, also stopped feeding. In an effort to maintain this position and speed up the respiratory exercise, it also speeds up the body’s consumption of oxygen. they