Blood - A question of SF

[den]

What would be a reasonable alternative to iron in blood? Would cobalt or manganese work? What colour would the blood be?

Comments

[makovette.livejournal.com]

Oxides of Manganese are dark grey to black iirc. Cobalt is most famously blue. I dunno the chemistry well enough off the top of my head to create a non-ferrous substitute for hemoglobin.

Look at the valence electrons of your candidate metals and see if you can cook up something semi-viable. Depends on the atmosphere the critter is breathing really. Cynide and Methane "blood chemistry" has been worked out iirc.

CYa!
Mako

[bookofnights.livejournal.com]

Horseshoe crabs have copper based blood. It's blue/green (http://www.beach-net.com/horseshoe/Bayhorsecrab.html) in color. (The last fact on the page.)

[acelightning.livejournal.com]

[dewhitton.livejournal.com]

Brilliant! Thanks!

[dewhitton.livejournal.com]

I'm working on a race that are Human (all the bits are in the same places) but have a different chemistry.

I always wondered how aliens could all eat the same food. I reckon they wouldn't have the same protiens or enzymes to digest them, and what's harmless to one could be dangerous to another.

[woodrunner.livejournal.com]

I was going to suggest copper as well but someone else beat me to it.

Other options are zinc, mercury, chromium, manganese, cobalt and cadmium. Of course, all these are toxic in normal human beings if they replace the ferrohemoglobin. Copper in particular aids in the absorption of iron into hemoglobin, so that would be a primary choice, but where the other metals are concerned, if they are present in the system in amounts that cannot be filtered (i.e. acute poisoning) they will start replacing iron in the blood.

Does it have to be a metal? It could easily be nitrite or a cyanidate compound..

[ursulav.livejournal.com]

No chemist am I, but I recall reading somewhere that some of the hypothetical aliens based on other metals (such as in the Star Trek universe, where you've got everybody and their brother based on cobalt or copper or whatever) would have a terrible time in an oxygen atmosphere, as their attempts to breathe would result in their lungs corroding, or in extreme cases, catching fire. I'm not sure if that would apply here (I think they might have been talking about the silicon based giant-cheese-pizza burrowing rock monster from the original Trek. (Fine! It was called the Horta. I'm a horrible, horrible geek, okay? *sob*)) but it's worth contemplating, just in case you wind up with something with blood more reactive to oxygen than is really safe.