We humans have red colour blood, a feature we share with the majority of the other creatures on the planet. But that is not the only colour possible. Some animals bleed not only in red, but in purple, blue, and even green. This article explains how, and why, that happens. Let’s take a look at what causes blood to have a certain color in each animal.
What is Blood?
Blood is a fluid within most animals that carries oxygen and nutrients to different parts of the body. It also transports metabolic waste products away from those same cells. There are four basic elements of the human blood: plasma, red blood cells, white blood cells, and platelets.
Why blood is Red?
Blood is red because it has an iron-containing substance called hemoglobin. Each hemoglobin protein is made up subunits called hemes. The hemes can bind iron molecules, and these iron molecules bind oxygen. Hemes give blood its red color.
Animals With different blood colour and Why?
Some animals have a special mix of plasma proteins in their blood. These proteins cause the many colors of the blood.
Hemocyanin Proteins – Blue Blood
- The blue color is derived from copper proteins present in the blood called hemocyanin.
- When the blood is oxygenated which contains copper proteins, it turns blue. Otherwise, it is colorless.
- The hemocyanin protein is a lot bigger than other blood proteins (like hemoglobin in human blood) and there it flows freely around in the blood of these animals.
1. Antarctic octopus
The big Antarctic octopus called Pareledone Charcoti which lives in the extremely cold waters around the North and South Pole has light blue-colored blood. The specific species of octopuses have around 40% or more hemocyanin in its blood to be able to live in the cold waters of Antarctic.
The Spider blood is pale blue because of hemocyanin. The spiders also use the blood pressure to get discarded of old skin (shedding) and that’s an important part of the life circle for some spiders.
The Horseshoe Crabs have blood that is light blue. That is also due to the hemocyanin in its blood. It also has no veins as the blood runs through an open circulatory system where it has direct access to the internal organs. So the blood has faster and easier access to the organs and blood veins are not needed.
Emperor scorpions have blue colour blood. It is the largest among the scorpion family. They have high levels of hemocyanin in their blood as well.
Hemerythrin Proteins- Purple Blood
- The purple color is derived from proteins present in the blood called hemerythrin.
- When the blood is oxygenated which contains proteins, it turns purple. Otherwise, it is colorless.
The Peanut Worms are marine animals with dark purple coloured blood and can appear almost black. The purple color is due to the protein called Hemerythrin. This protein also helps them to fight infections. It helps worms regenerate when a part of it is cut off. Hemerythrin plays a vital part in that process.
Brachiopods are marine organisms commonly called lamp shells also have dark purple blood. The blood circulates when the tiny heart pumps it around in the animal. The blood circulates to deliver nutrients to the animal.
Chlorocruorin Protein- Green Blood
- The green colour is derived from the proteins present in the blood called chlorocruorin.
- It is another oxygen-binding protein found in the plasma of the blood.
Leeches have blood containing the protein called chlorocruorin. It causes the blood to turn green. They are blood-sucking parasites. They are quite unique because they have sucking mechanisms on both ends.
Biliverdin Pigment- Green blood /bone
- The green color is caused by a pigment called Biliverdin.
- It is the same pigment that will sometimes turn your skin green when you have a wound or took a hit.
It is the same pigment that turns the tobacco hornworm into the beautiful bright green. Almost all the animals with green blood eat green vegetation.
The skink belongs to the lizard family. They thrive with a high level of biliverdin in its blood and that causes the blood to turn green. The green pigment is also present in the muscles and bones.
Another reptile with green blood is the which is a small green salamander found in New Guinea.
- The yellow color is caused by the metal called vanadium which is found in Vanabin proteins.
- Animals have these high concentrations of vanabin as it doesn’t help the circulation of oxygen.
Beetles have yellow-ish blood like several other bugs. Insects don’t even have blood vessels. Instead, they have a large hole inside the skeleton where all the blood resides.
Sea Cucumbers are weird animals. They live down at the bottom of the ocean and are very simple animals. The reason for the yellow color is found in the proteins of the blood. It has a high concentration of vanabin.
- The White or clear blood colour is derived due to lacks the proteins hemoglobin and hemocyanin in blood.
1.The Ocellated Icefish
This special type of fish has white translucent blood. It doesn’t have scales like other fish. It can live in water that is below the freezing temperature. Water can still be liquid below the freezing point when there are sufficient levels of salt dissolved in the water.
Cockroaches are also known to have white blood and you will notice it when you smack them.