# Blue blood and other colors...

**URL:** <https://boards.straightdope.com/t/blue-blood-and-other-colors/440508>\
**Category:** Cecil's Columns/Staff Reports\
**Created:** [March 7, 2008, 9:15pm UTC](https://boards.straightdope.com/t/blue-blood-and-other-colors/440508 "2008-03-07T21:15:30Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![mwbrooks](https://avatars.discourse-cdn.com/v4/letter/m/ba9def/32.png) [@mwbrooks](https://boards.straightdope.com/u/mwbrooks)\
**Post date:** [March 7, 2008, 9:15pm UTC](https://boards.straightdope.com/t/blue-blood-and-other-colors/440508/1 "2008-03-07T21:15:30Z")

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Regarding [Are flamingos pink because they eat shrimps?](http://www.straightdope.com/columns/010518.html) and perhaps [If blood is red then why do your veins look blue?](http://www.straightdope.com/mailbag/mbloodrd.html)…

Someone in a closed thread mentioned that horseshoe crabs have blue blood. I had heard somewhere that this is because their version of “hemoglobin” is based on copper, and that by the same token plants’ chlorophyll is “the same” molecule, based on magnesium. From elsewhere I gather that this is _ **not** _ true, but in fact that there are lots of different colors of blood among various species, and in fact that the difference hinges on the metal in their blood pigments (which may or may not carry oxygen). Among them:

[ul]  
[li]Red–iron–mammals, etc.[/li][li]Green–magnesium–plants (chlorophyll)[/li][li]Also Green–vanadium–sea squirts[/li][li]Also Green–(iron? large hemoglobin assemblages)–bristleworms[/li][li]Purple–“binuclear” iron–penis worms[/li][li]Blue–copper–octo- and arthropods[/li][li]Clear/grey–no oxygen-binding pigment–certain fish[/li][/ul]

I got this from [Hemoglobin And It’s Substitutes](http://www.idiocentrism.com/hemoglobin.htm). Obviously this is a very simple presentation of something vastly complex. Does it carry a grain of truth?

Just curious. One hears things and wonders.

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**Author:** ![Una\_Persson](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/una_persson/32/346_2.png) [@Una\_Persson](https://boards.straightdope.com/u/Una_Persson)\
**Post date:** [March 8, 2008, 4:13am UTC](https://boards.straightdope.com/t/blue-blood-and-other-colors/440508/2 "2008-03-08T04:13:58Z")

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Very prescient of you. I saw a draft of a soon-to-be upcoming column by Cecil, where he talks about blue blood and horseshoe crabs, and I think he mentions vanadium blood too. Are you sure you’re not sitting in a hotel room in Chicago watching Cecil through a 50x terrestrial telescope? :dubious:

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**Author:** ![mwbrooks](https://avatars.discourse-cdn.com/v4/letter/m/ba9def/32.png) [@mwbrooks](https://boards.straightdope.com/u/mwbrooks)\
**Post date:** [March 8, 2008, 5:08am UTC](https://boards.straightdope.com/t/blue-blood-and-other-colors/440508/3 "2008-03-08T05:08:20Z")

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[QUOTE=Una Persson]  
Very prescient of you. I saw a draft of a soon-to-be upcoming column by Cecil, where he talks about blue blood and horseshoe crabs, and I think he mentions vanadium blood too. Are you sure you’re not sitting in a hotel room in Chicago watching Cecil through a 50x terrestrial telescope? :dubious:  
[/QUOTE]

Nah. Cecil’s the one who saw _my_ question coming. He sensed that I was _incredibly_ bored today. 😉

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**Author:** ![DSYoungEsq](https://avatars.discourse-cdn.com/v4/letter/d/c6cbf5/32.png) [@DSYoungEsq](https://boards.straightdope.com/u/DSYoungEsq)\
**Post date:** [March 10, 2008, 8:45pm UTC](https://boards.straightdope.com/t/blue-blood-and-other-colors/440508/4 "2008-03-10T20:45:29Z")

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[QUOTE=mwbrooks]  
Does it carry a grain of truth?

Just curious. One hears things and wonders.  
[/QUOTE]

Ask Spock. 😛