# Oxygen carriers in animal blood. Iron, Copper, Vanadium (?) ? **URL:** \ **Category:** Factual Questions\ **Created:** [June 13, 2020, 4:17pm UTC](https://boards.straightdope.com/t/oxygen-carriers-in-animal-blood-iron-copper-vanadium/855611 "2020-06-13T16:17:58Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![am77494](https://avatars.discourse-cdn.com/v4/letter/a/d2c977/32.png) [@am77494](https://boards.straightdope.com/u/am77494)\ **Post date:** [June 13, 2020, 4:17pm UTC](https://boards.straightdope.com/t/oxygen-carriers-in-animal-blood-iron-copper-vanadium/855611/1 "2020-06-13T16:17:58Z")
Most animals use iron to transport oxygen through their blood system. Some mollusks use copper to do the same job. There’s an unproven theory that some other animals used Vanadium ([Vanabin - Wikipedia](https://en.m.wikipedia.org/wiki/Vanabins#Vanabins_as_oxygen_carriers)) During evolution, are there any other metal or non-metals that were tried by living creatures ? ---
**Author:** ![Senegoid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/senegoid/32/6606_2.png) [@Senegoid](https://boards.straightdope.com/u/Senegoid)\ **Post date:** [June 13, 2020, 10:27pm UTC](https://boards.straightdope.com/t/oxygen-carriers-in-animal-blood-iron-copper-vanadium/855611/2 "2020-06-13T22:27:07Z")
What color blood do those mollusks have? Copper compounds tend to be greenish. In the Star Trek stories, Spock was said to have green blood because it was copper based. Would animals with copper-based oxygen-carrying molecules have green(ish) blood? ---
**Author:** ![Ike\_Witt](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ike_witt/32/283_2.png) [@Ike\_Witt](https://boards.straightdope.com/u/Ike_Witt)\ **Post date:** [June 13, 2020, 11:16pm UTC](https://boards.straightdope.com/t/oxygen-carriers-in-animal-blood-iron-copper-vanadium/855611/3 "2020-06-13T23:16:01Z")
[Horseshoe Crab](https://www.reddit.com/r/interestingasfuck/comments/a1zi45/horseshoe_crab_blood_is_blue_and_costs_60000_per/) blood. ---
**Author:** ![Broomstick](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/broomstick/32/246_2.png) [@Broomstick](https://boards.straightdope.com/u/Broomstick)\ **Post date:** [June 14, 2020, 9:29am UTC](https://boards.straightdope.com/t/oxygen-carriers-in-animal-blood-iron-copper-vanadium/855611/4 "2020-06-14T09:29:34Z")
Horseshoe crab blood uses [hemocyanin](https://en.wikipedia.org/wiki/Hemocyanin), which is copper-based. I cranked up the way-back machine, having a vague memory of prior threads and found a couple [The Colors of Blood](https://boards.straightdope.com/sdmb/showthread.php?t=104897) [Spider Blood](http://boards.straightdope.com/sdmb/showthread.php?s=&threadid=69786) - this one has a bunch more detail. ---
**Author:** ![MrDibble](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mrdibble/32/114_2.png) [@MrDibble](https://boards.straightdope.com/u/MrDibble)\ **Post date:** [June 14, 2020, 11:01am UTC](https://boards.straightdope.com/t/oxygen-carriers-in-animal-blood-iron-copper-vanadium/855611/5 "2020-06-14T11:01:04Z")
> [@Senegoid](#): > > What color blood do those mollusks have? Copper compounds tend to be greenish. In the Star Trek stories, Spock was said to have green blood because it was copper based. > > Would animals with copper-based oxygen-carrying molecules have green(ish) blood? Blue. When oxygenated. Colourless, when not. Generally, as soon as you bleed them, it’s going to turn blue regardless. There are [pictures](https://cdn.theatlantic.com/thumbor/0JKy2mAzHfWnbACAYTeH3PPZ8_o=/332x42:2000x980/720x405/media/img/mt/2017/01/Screen_Shot_2017_01_10_at_11.04.40_AM-1/original.jpg)out there of rows of horshoe crabs being bled into bottles. It’s quite disturbing. And now you know where the blue milk _really_ comes from, Star Wars fans. Banthas, my ass. 😃 ---
**Author:** ![MrDibble](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mrdibble/32/114_2.png) [@MrDibble](https://boards.straightdope.com/u/MrDibble)\ **Post date:** [June 14, 2020, 11:09am UTC](https://boards.straightdope.com/t/oxygen-carriers-in-animal-blood-iron-copper-vanadium/855611/6 "2020-06-14T11:09:51Z")
> [@am77494](#): > > During evolution, are there any other metal or non-metals that were tried by living creatures ? Forgot to address this: Yes, there’s the manganese-containing pinnaglobin.