Fish are aquatic vertebrate animals that are typically ectothermic ( previously cold-blooded ) , covered with scales , and equipped with two sets of paired fins and several unpaired fins .

鱼是水生脊椎动物，典型特征是属冷血动物，全身有鳞片，有一对鱼鳍或几个不成对的鱼翅。

Mobile ectothermic animals can control their body temperatures by selecting specific thermal conditions in the environment , but embryos-trapped within an immobile egg and lacking locomotor structures-have been assumed to lack that ability .

变温动物可以在特殊的热条件环境中控制他们的体温，但对于胚胎来说，被困于蛋中，由于结构，而缺少运动，已经是被假设缺乏的能力。