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View submission: Ask Anything Wednesday - Engineering, Mathematics, Computer Science
What kind of chemical composition, atmosphere, etc. would be needed for beings with blue blood to exist? Is there something unique to Earth that means most animals have red blood?
Blue blood animals exist right here on earth, using hemocyanin[1]. The most famous example is horseshoe crabs, you can see a pic here[2] which describes how medically useful horseshoe crab blood is (not necessarily because it's blue).
1: https://en.wikipedia.org/wiki/Hemocyanin
2: https://www.nhm.ac.uk/discover/horseshoe-crab-blood-miracle-vaccine-ingredient.html
As far as I know, hemocyanin and hemoglobin are vaguely comparable and the main reason most animals you know of have red blood is because they are vertebrates, and all have kept the same basic molecule of hemoglobin from the ancestral vertebrates that used it. They don't come by it independently, it comes from a common source. If the earliest vertebrate had happened to use hemocyanin, we'd all be using that.
There's nothing here!