Red is the most common blood colour found in living beings, including humans and animals; since childhood, red has been the only colour that represents blood in our minds.
However, these 5 animals do not have red blood in their bodies.
Crocodile Icefish: These fish are found in harsh cold climates where freshwater freezes, lowering red blood cell counts and turning red blood cells into liabilities. Blood is a colourless liquid.
Horseshoe Crab: Horseshoe crabs resemble spiders more than other arachnids, and they share hemocyanin-filled blue blood with them.
Green-blooded skinks of New Guinea: The skink family comprises several lizard species that have lime green blood in New Guinea.
Octopus: blood has a distinct appearance from human blood due to the presence of the latter protein. Blood rich in hemocyanins turns blue due to the copper when it oxygenates.
Brachiopods: Hemerythrin imparts a colourless or slightly yellow appearance to deoxygenated blood. But as soon as the blood begins to absorb oxygen, it turns violet to pink in colour.