It may be red in humans and in other mammals, but octopus, for example, have blue blood and ocellated ice fish have blood that is completely clear, and in Papua New Guinea, they are green-blooded shanks.
人类和其哺乳动物的血可能是红色的,但比如章鱼的血是蓝色的,眼斑雪冰鱼的血是完全透明的,而在巴布亚新几内亚,它们的血是绿色的。