Additionally, arterial blood and venous blood can also differ in color due to varying oxygen levels. Blood with a high oxygen content appears bright red, usually arterial blood, while blood with a low oxygen content appears dark red, typically venous blood. Most blood donations or blood tests use venous blood, so it appears dark red externally. If the blood contains more methemoglobin or other hemoglobin derivatives, it looks purplish-black. Plasma, due to a small amount of bilirubin, appears transparent pale yellow; if it contains chylomicrons, it appears milky and cloudy; if hemolysis occurs, it results in red plasma.
In short, apart from some rare disease patients, most should still see red.
This is also the most common blood color among vertebrates, including humans, mammals, most fish, amphibians, reptiles, and birds.
However, at this moment, Wang Ye's blood is pure black,
so black that not a hint of red can be seen.
Not even light can pass through it.
