Do you know why octopuses have blue blood?
Miscellaneous / / April 02, 2023
The nobility of the clam family has nothing to do with it.
"Blue blood" often called people of aristocratic origin. They did not work in the fields like peasants, they did not sunbathe, and therefore their skin was pale. And through it bluish veins were clearly visible. True, the blood flowed through them the most ordinary. So this expression is just an idiom.
But creatures with blue blood still exist in nature, and these are not aristocrats, but octopuses and squids.
Why do they have blue blood? Well, for starters, it’s worth figuring out why we have it red. Everything is quite simple: such a shade of blood gives hemoglobin - a protein containing iron. It is able to carry oxygen throughout the body in order to saturate tissues with it. Appeared hemoglobin more than 400 million years ago in a common ancestor of humans and sharks.
Cephalopods, on the other hand, are further away from us on the evolutionary tree, and they went along a different branch of development, deciding to keep the older, familiar protein - hemocyanin. It is found in the blood of mollusks and the hemolymph of arthropods.
It is hemocyanin that is used in octopuses to carry oxygen from the gills and skin throughout the body. He more efficient works in the cold waters of the ocean, but makes the blood more viscous, so these creatures have rather high blood pressure - it can exceed 75 mm Hg. Art.
Hemocyanin, unlike hemoglobin, does not contain iron, but copper. This is what gives the blood of octopuses a blue tint.
Despite this difference, their circulatory system is quite decent. Octopuses have as many as three hearts: two smaller ones for pumping blood during breathing - at each gill - and one main one. The latter is turned off when the mollusk swims and is activated when it crawls. The main heart of octopuses quickly overworks, so they prefer to move along the bottom, rather than swim.
By the way, hemocyanin does not make the blood blue in all animals. For example, in some crabs, its composition differs from that of the octopus, and their tissues are colored purple.
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