Bloody creatures

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Why is our blood red? Do we share the same blood colour with every creature on this planet? If not, why do they have a different colour?

Well, to start with, our blood is red because of the red blood cells in human body. These tinny cells get their red pigment from a protein called haemoglobin. Hemes, the subunits of this protein, bind iron molecules and those bind oxygen. So our blood is red because of the interaction between iron and oxygen, as iron has the property of reflecting red light.

However not all blood is red.

Animals may have red, green, blue, violet, orange, or colourless blood. This happens because some have haemoglobin like us and some have different respiratory pigments.

Cockroaches have white blood.

As if they were not enough disgusting, they have a shitty blood colour as well. This is because they lack haemoglobin. However the blood of a female can be slightly orange when she is carrying eggs. This happens due to the protein vitellogenin that is present in the blood. So if you ever kill a cockroach and bleeds orange, you will know that you have just killed a mama.

Octopuses and lobsters have blueish blood.

Their blood instead of haemoglobin contains haemocyanin, which transports oxygen and contains copper instead of iron. When oxygenated it’s becoming blue and in its deoxygenated form is colourless. Both delicious and cool colour blooded.

Earthworms and leeches have green blood.

They bleed green because of chlorocruorin (which has nothing to do with chlorine atoms), a protein that is very similar in appearance to haemoglobin. Suck our red blood leeches!

Marine worms have violet blood.

This colour is caused by another different respiratory pigment, haemorythrin, which contains individual units and themselves contain iron atoms. When oxygenated is bright violet and when deoxygenated the blood is colourless. If you ask me, I would love to have violet blood (by not being a marine worm though).

Corals and jelly fish have no blood at all.

They do not have a circulatory system, so they have no blood. They obtain oxygen as well as nutrients directly from their environment. The cells on the outside of their body that come in contact with water get everything they need by diffusing them into their body. No blood, no comment.

Sources:
https://en.wikipedia.org/wiki/Hemoglobin
http://scienceline.ucsb.edu/getkey.php?key=2419
https://owlcation.com/stem/Blood-Color-in-Humans-and-Animals-Meaning-and-Function
http://www.compoundchem.com/2014/10/28/coloursofblood/
http://scienceline.ucsb.edu/getkey.php?key=4817