5. Red: Good to be red-blooded, sanguine, ruddy, strong. Of course, if it appears in a vampire story, it’s invaribly “crimson,” but we know what they mean.
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4. Yellow: Insects have yellow blood, which will be familiar to anyone who’s ever stomped a large cockroach. Insect blood doesn’t transfer oxygen, which means it doesn’t need hemoglobin (what makes our blood appear red). Insect blood consists of only 10% hemocytes (blood cells), most of it just watery plasma called hemolymph, tending to be green or . . . yuck, yellow.
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3. Green: Moviemakers like to give aliens green blood. My brother, Dave, insists it helps them keep a PG rating while bucketing alien blood all over the place. Sometimes it is acidic, as with Ridley Scott’s Alien. The most famous alien to have green blood is probably Mr. Spock. Dr. “Bones” McCoy cites Spock’s blood color whenever he levels a speciesist [sic] taunt against the supremely rational being, as here:
Spock: I was trying to comprehend the meaning of the words.
McCoy: It’s a song, you green-blooded . . . Vulcan. You sing it. The words aren’t important. What’s important is that you have a good time singing it.
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2. Blue: Ah, nobility, wealth, supposedly superior genes and stuff. Must be nice. Wiki explains: “Blue blood is an English idiom recorded since 1834 for noble birth or descent; it is also known as a translation of the Spanish phrase sangre azul, which described the Spanish royal family and other high nobility who claimed to be of Visigothic descent, in contrast to the Moors.” Blue bloods are often spotted in places like Hilton Head, Aspen, the US Senate, and at various cotillions, where they look at one other and smile.
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1. Clear: That’s right. Lobsters have clear blood, but it turns white when they die. Cool.