August 13, 2002

Blue Blood

Last week I learned--I really don't think I had ever known it before--that the copper-based non-hemoglobin blood of horseshoe crabs turns bright blue when oxygenated.

I had always thought that it turned green--after all, Mr. Spock on "Star Trek" had copper-based blood, and it turned green when he bled. But it turns out not to be so: blue, not green.

When you can't trust "Star Trek" as a reliable source on matters of elementary extraterrestrial biology, it's clear that the world is a damned dangerous and unfriendly place...

Posted by DeLong at August 13, 2002 08:39 PM | TrackBack

Comments

It just means that the chemistry of Vulcan blood is not the same as the chemistry of crab blood. Is this a surprise? Hmm.

Posted by: Matt on August 14, 2002 08:04 AM

____

Love your nature comments. Love horseshoe crabs.

randall

Posted by: randall on August 14, 2002 09:11 AM

____

Are you trying to tell me... Star Trek is fiction?

Posted by: Dave Romm on August 14, 2002 10:39 AM

____

Maybe the Enterprise was over-pressured in oxygen (hence Dr. Spock's copper-based blood faster oxydation) to keep the crew high in spite of their being lost at the edge of the universe...

Here is a replicable experience to check my hypothesis : bleed a few horseshoe crabs in a Vegas casino :)

Posted by: Jean-Philippe Stijns on August 14, 2002 12:22 PM

____

I meant pressurized of course...

Posted by: Jean-Philippe Stijns on August 14, 2002 12:23 PM

____

The copper-containing oxygen carriers in Mollusca (octopi and snails) and Arthropoda (lobsters and scorpions) are called hemocyanins. Upon oxidation the colorless protein becomes blue.

Posted by: Seva Rostovtsev on August 14, 2002 05:27 PM

____

And now it is time for the big question: why? Why did blood have to evolve twice? And why once with copper and once with iron at the core of the molecule? Just what is it about carrying oxygen that demands a huge honking metal atom at the center of the key molecule?

Posted by: Brad DeLong on August 15, 2002 07:57 AM

____

Brad,

Brilliant Question. Will ask.... We do love nature.

Posted by: on August 15, 2002 08:53 AM

____

Blood? Your species has blood?

Posted by: Dr. Zoidberg on August 15, 2002 09:54 PM

____

>>Blood? Your species has blood?<<

Touché...

Posted by: Brad DeLong on August 16, 2002 05:24 PM

____

Maybe Vulcan blood has some other pigmentation

in it besides the blue one. Perhaps there is a

yellow pigmentation caused the the T-type protein

that is one of the blood types of Vulcans. When

you add yellow to blue it turns green doesn't it?

Posted by: on December 10, 2002 10:04 PM

____

Maybe Vulcan blood has some other pigmentation

in it besides the blue one. Perhaps there is a

yellow pigmentation caused the the T-type protein

that is one of the blood types of Vulcans. When

you add yellow to blue it turns green doesn't it?

Posted by: on December 10, 2002 10:06 PM

____

Maybe Vulcan blood has some other pigmentation

in it besides the blue one. Perhaps there is a

yellow pigmentation caused the the T-type protein

that is one of the blood types of Vulcans. When

you add yellow to blue it turns green doesn't it?

Posted by: James T. on December 10, 2002 10:08 PM

____

To understand it, you need to know some stuff about basic biochemistry. Each hemoglobin molecule has an iron atom at the center of it. When deoxygenated blood passes through the alveoli in your lungs, the oxygen atoms bond to the iron atoms. The iron in the hemoglobin is what "carries" the oxygen around the body.

Of course, there's no real reason it should be limited to iron. There are several other elements that can bond to oxygen, and as our friend the horseshoe crab demonstrates, copper is one of them.

By the way, oxidized iron is red, and oxidized copper is blue-green.

Why did blood evolve twice? Who knows? Why did eyeballs evolve twice? Squid eyes are not the same type of eyes as human eyes. Molluscs split off our branch of the evolutionary tree long before eyeballs were evolved. Similarly, arthropods split off our branch before blood was evolved. Long time ago, eh?

Posted by: Bizud on December 17, 2002 03:49 PM

____

Ok here is a factoid, hemoglobin has iron (red blood), hemocyanins have copper (blue blood), and chlorophyll has magnesium (green leaf color).
These are identical molecules except for the mentioned metals.

Question, for the Dr.Spock wana bees, Why dose iron and copper cary oxygen and magnesium convert 6CO2+6h20 into C6H12O6(sugar) and 6O2's.

Posted by: John C. on December 11, 2003 03:21 AM

____

Post a comment
















__