Why is Octopus Blood Blue?
Most animals on earth have red blood but some animals like octopus have blue blood. Why it is so? what makes octopuses blood appear blue? What is its significance? what is the difference between red blood and blue ones? This post tries to answer these questions.
If you look around in your surroundings you will see different kinds of animals. They are quite different from each other, they show great morphological and physiological diversity but one that that you will find common is the colour of their blood. It's all red. And then comes an octopus and you realize that it's not all red. There is some blue also present in some animals, of which one most prominent example is an octopus. So the question arises why it is so. Why do we and most animals have red blood but the octopus has blue? The answer to this question lies in the fact that why even we need blood why just simple water flows in our veins? Lets first answer this because once you understand this then the question of why octopus has blue blood will seem to you as a trivial problem.
So what is the working of blood in the body?
Blood is a body fluid found in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells.
So now you know that one of the main functions of blood in addition to other things is to carry oxygen to various constituent cells of the body. For this purpose, blood has some binding agent which binds the oxygen with blood which is then carried to other cells. In most cases like in our case, this agent is haemoglobin. Which is an iron-containing protein this iron binds the oxygen and carries it with blood? Our blood appears only due to the presence of this iron in our blood. Just like the surface of Mars appears red due to the high presence of iron in its soil. But haemoglobin is not the only one in the market there is also another protein called Hemocyanins (also spelt haemocyanins) which can function similar to haemoglobin. Hemocyanin is responsible for keeping the species alive at extreme temperatures. It is a blood-borne protein containing copper atoms that bind to an equal number of oxygen atoms. It's part of the blood plasma in invertebrates.
Octopuses have a closed circulatory system, in which the blood remains inside blood vessels. Octopuses have three hearts; a systemic heart that circulates blood around the body and two branchial hearts that pump it through each of the two gills. The systemic heart is inactive when the animal is swimming and thus it tires quickly and prefers to crawl. Octopuses' blood contains this copper-rich protein haemocyanin to transport oxygen. This Hemocyanin makes the blood very viscous and it requires considerable pressure to pump it around the body. In cold conditions with low oxygen levels, haemocyanin transports oxygen more efficiently than haemoglobin. The haemocyanin is dissolved in the plasma instead of being carried within blood cells and gives the blood a bluish colour. The hemocyanin allows octopuses to get a steady oxygen supply, even when it isn't readily available in their environment or when it swims. It also ensures that they survive in temperatures that would be deadly for many creatures, ranging from temperatures as low as 28 degrees Fahrenheit (negative 1.8 degrees Celsius) to superheated temperatures near the ocean's thermal vents. To survive in the deep ocean, octopuses evolved a copper rather than iron-based blood called hemocyanin. Because this copper base is more efficient at transporting oxygen than haemoglobin when the water temperature is very low and not much oxygen is around. We did not develop this because we live in normal conditions where iron-based haemoglobin is more efficient and better than hemocyanin, therefore, we have red blood but octopuses have a blue one. One interesting point to note here is that octopuses' blood is actually transparent; it appears blue because Oxygenation causes the colourless Cu(I) in deoxygenated blood to turn blue coloured Cu(II) when it gets oxygenated.
I hope that now you have understood why octopus has blue coloured blood instead of red. For more interesting things like this please stay with us and subscribe to our blog to get notifications for our newer posts and stay updated with us. Thank you and stay curious.