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.
人类哺乳动物血可能是红色,但比如章鱼血是蓝色,冰鱼血是完全透明,而在巴布亚新几内亚,它们血是绿色。