7 fascinating creatures with blue-coloured blood

When we think of blood, the colour red usually comes to mind. But in the animal kingdom, some creatures have blood that appears blue due to a very different oxygen-transport system. Instead of using iron-rich hemoglobin like humans, these animals use a copper-based molecule called hemocyanin, which turns blue when it binds with oxygen. The result is a series of truly fascinating animals whose blood defies the norm and supports their unique ways of life.

Horseshoe crabs have been classified amongst the most common ‘blue blood’ animals in the world. These prehistoric animals are marine arthropods; however, their blood contains hemocyanin instead of hemoglobin in order to facilitate the transportation of oxygen in their bodies. ‘Blue blood’ is more than just aesthetically pleasing; it is also immensely useful in medical science because one of its ingredients tests for contamination in medical instruments.

Octopuses are famous for their intelligence and ability to adapt to their surroundings. Moreover, they have blue-coloured blood. The hemocyanin present in their bloodstream is copper-based and allows them to easily live in environments with low oxygen content. This enables them to easily transport oxygen even when iron-based bloodstream would not have been capable of doing so in such environments.

Like their cephalopod cousins, squids have blue blood because of hemocyanin. Their circulatory system is specially adapted for life in the ocean’s depths, where oxygen levels can be low. Squids rely on this copper-based system to carry oxygen to tissues efficiently, enabling them to be fast, agile predators in a world where red blood would not function as well.

Despite the fact that scorpions are land arthropods, they also have blue blood. The reason they can thrive in arid circumstances with low oxygen is because of the hemocyanin found in the bodily fluid. It is thought to have been inherited from ancient ancestors and is connected to life in the sea.

The lobster has blue blood that runs through its entire body. This enables it to breathe in the water that is cold and lacks enough oxygen. The presence of water in its body makes its copper-based blood even more blue in colour. Perhaps this is one reason why the lobster thrives in the water.

Marine snails possess blue blood due to hemocyanin. Marine snails can be found in various oceanic environments, ranging from shallow areas around reef formations to deeper sections. The composition of their blue blood makes it possible for them to obtain sufficient oxygen from their surroundings. The blue blood of marine snails is indeed an interesting adaptation for survival.

Spiders lack an impressive appearance, but the fact is that most species possess blue-coloured hemolymph within their blood vessels; hemolymph is basically blood. The blue pigment gets along due to hemocyanin. The oxygen transport system is effective within the body of the spider, as they are quite agile and can hunt effectively even in low oxygen situations like burrows.

The variety of blood colours found in nature demonstrates how evolution has come up with a range of solutions for a biological problem. This problem is oxygen transport. In the oceans, there are large creatures such as octopi. In the deserts, there are hunters such as scorpions and spiders. Blue blood is an ingenious solution that enables organisms to survive in biomes where red blood may not be as effective. The next time you learn about blood, remember how inventive nature is.