‘No red blood, no problem’: Discover animals with green, purple, and blue blood

Maybe I’m used to animals bleeding red, like humans; I’ve always believed every animal does. But I was wrong. Because there are other colours of blood that run on some animals. 

The reason for red blood is the presence of “haemoglobin” — it binds with oxygen and then allows red blood cells to circulate and supply other cells in the body. 

“Hemerythrin” is an iron that is attached to oxygen molecules to form a purple-pink blood. Blue blood is due to “hemocyanin” — a protein that contains copper. At the initial stage, the protein is colourless but becomes blue after coming in contact with oxygen. 

Let’s not drag it further, I’ve come up with a detailed list of animals with no red blood:

1 Crocodile Icefish

Crocodile Icefish live in the ocean, particularly in Antarctica. No red blood cells or hemoglobin yet they survive in a condition that kills other animals. They absorb oxygen from the ocean and, afterwards, send it to their bloodstream. The blood of this fish is colourless. Regardless, it travels to any length.

2. Octopuses

Octopuses have bluish blood. Another interesting thing is that they have three hearts which pump blood. Actually, in deep-sea environments, hemocyanin is better at carrying oxygen through an animal’s vein. It also helps in regulating the salt content of octopus blood to match the water they are swimming in. Water acidity can be very disturbing to octopus survival because a change in water pH can affect hemocyanin in binding with oxygen.

3. Horseshoe Crabs

Horseshoe crabs have been very useful in treating ailments due to their blood colour. Although, they are not true crabs as their name suggests but close to spiders. Their blood is blue, and filled with hemocyanin. The lack of white blood cells makes them not vulnerable to harmful viruses and bacteria in the ocean. 

The cells inside horseshoe crabs are called “amoebocytes” — in case of intrusion, it release a gel and enclose a bacterium. Unwanted bacteria are prevented from spreading through this.

4. New Guinea Skinks

There is a type of lizard in New Guinea called “prasinohaema” — it is a green-blooded skink. Its bones, tongue and muscles are very bright and lime-green due to “biliverdin” — which is toxic and causes jaundice. Despite having 40 times higher green bile than human beings, they are still very healthy.

5. Peanut worms

Peanut worms are animals with purple blood. It is due to hemerythrin — which binds oxygen at a greater level than most haemoglobin variants. It can help with iron storage and immune function. The translucent skin of some peanut worms makes the colour of their blood, purple visible