Wiktionary
alt. (context biochemistry English) a blue copper-containing respiratory pigment (a metalloprotein) found in most molluscs, and some arthropods n. (context biochemistry English) a blue copper-containing respiratory pigment (a metalloprotein) found in most molluscs, and some arthropods
Wikipedia
Hemocyanins (also spelled haemocyanins and abbreviated Hc) are proteins that transport oxygen throughout the bodies of some invertebrate animals. These metalloproteins contain two copper atoms that reversibly bind a single oxygen molecule (O). They are second only to hemoglobin in frequency of use as an oxygen transport molecule. Unlike the hemoglobin in red blood cells found in vertebrates, hemocyanins are not bound to blood cells but are instead suspended directly in the hemolymph. Oxygenation causes a color change between the colorless Cu(I) deoxygenated form and the blue Cu(II) oxygenated form.
Usage examples of "hemocyanin".
Chromatophores ignited within the flesh, and its color changed from maroon to a lighter, brighter red not a bloodred, for so permeated was its blood with hemocyanin that it was in fact green, but a red designed by Nature purely for intimidation.
In us, the oxygen is carried to the tissues, and the carbon dioxide carried away by an iron compound, hemoglobin, but in many animals of Earth, the same function is performed by a copper compound, hemocyanin, which is an intense blue.
Hemoglobin, such as in our blood, and hemocyanin, like that in the blue blood of the Venerians, are practically unique in that respect.