牛蛙蝌蚪一般经越冬至5月末6月初,当气温回升到24℃以上时,开始发生变态。牛蛙由蝌蚪(幼体)转变成成体这一过程,称为变态,整个变态时间约70—80天。但在整个变态中有两个危险期:一是在前肢即将长出的阶段,此时,蝌蚪的呼吸由鳃转为肺进 Bullfrog tadpoles generally through the winter solstice late May early June, when the temperature rose to above 24 ℃, began to occur metamorphosis. Bullfrog from tadpoles (larvae) into adults in the process, called metamorphosis, the entire metamorphosis time of about 70-80 days. But there are two dangerous periods throughout the metamorphosis: one is about to grow out of the forelimbs, when the tadpoles’ respiration changes from gills to lungs