What atoms or molecules can bind oxygen like iron does in blood?

[newjerseyrunner]

I have an alien in one of my stories that bleeds. I want to use science to determine what the range of possible colors would be. It's an oxygen breathing alien, so it's blood has to be efficient at transporting it. I know our blood is red because we use iron to do that. I don't know enough about the chemistry of how oxygenation works to come up with any guesses for anything else.

First off: What other atoms or molecules can bind so easily with oxygen? I know copper reacts with oxygen to turn green, how easy is that process compared to iron?

 

[Vanadium 50]

Why do you suppose the same chemical that carries oxygen has to be the one that causes the color?

 

[snorkack]

Why do you suppose the same chemical that carries oxygen has to be the one that causes the color?

One obvious reason: hemoglobin does both. Another: a chemical that carries oxygen is needed in large amounts. If it has colour, it would prevail over other coloured compounds in blood.

 

[Ryan_m_b]

Here's a handy guide for different blood colours that occur in nature:

 

[Bandersnatch]

Here's a handy guide for different blood colours that occur in nature:

There's more options:
https://owlcation.com/stem/Blood-Color-in-Humans-and-Animals-Meaning-and-Function

 

[newjerseyrunner]

I had no idea that Earth life had that kind of diversity in their blood. I thought most blood was mostly clear. I'm going to have to look through them and see what's most efficient. This creature is highly intelligent, and therefore has a huge energy requirements.

 

[Vanadium 50]

Another: a chemical that carries oxygen is needed in large amounts. If it has colour, it would prevail over other coloured compounds in blood.

But it doesn't have to be colored. Fluosol, for example, is kind of milky, and works just fine as blood. Mix that with something orange, and presto! Orange blood. Or chartreuse. Or mauve. Or...

 

[Skyland]

Here's a handy guide for different blood colours that occur in nature:

View attachment 189536

Penis worms have violet blood, neat.

 

[Outdoors Mom37]

I seen someone or something's blood orange?

 

[symbolipoint]

I have an alien in one of my stories that bleeds. I want to use science to determine what the range of possible colors would be.

Why must he bleed? If he is not made to bleed, then you can stop worrying about what kind of blood has has and its color.

 

[256bits]

Why must he bleed? If he is not made to bleed, then you can stop worrying about what kind of blood has has and its color.

Maybe the alien gets bloodshots eyes when he is over tired, or gets embarassed quite easily( assume he has a similar response to this as humans ). His blood color could show through somehow, even if he does not bleed.

 

[symbolipoint]

@256bits, post #11 is clever. I would also wonder: Does the animal need to be like Mammal, or may it be some other taxonomic category? Only the author ( @newjerseyrunner ) would know this.

edit add: I say this since a different taxonomic category could be important in what kind of blood the animal uses.