The color of blood is also influenced by the concentration of hemoglobin, which is the special protein for transporting oxygen in red blood cells and the protein for making blood red. The higher the hemoglobin content, the darker the blood color. The normal value of hemoglobin is slightly different due to gender and age, and the neonatal hemoglobin is the highest, which gradually decreases with age. The normal value of hemoglobin in adult males is 120- 165g/L, and in females it is1150g/L. ..
In nature, the blood of animals has many colors, and the color of blood is determined by the color of hemoglobin which is responsible for transporting oxygen in blood.
Hemocyanin is a copper-containing protein. This protein uses two copper atoms (Cu) to connect an oxygen atom (O2), which turns blue after oxidation and colorless after reduction. Hemoglobin is a respiratory protein containing iron porphyrin, which is red when combined with oxygen (high concentration solution is light red, and dilute solution is green). Hemoglobin is a pigment protein, which exists in the blood of all vertebrates (including humans) and some invertebrates. Hemoglobin is red, so blood is red.
The blood of earthworms is blue-green. A small ring worm that lives in crevices in rocks by the sea. Its blood is bright green, so is the blood of squid. The blood of prawns, sea crabs and hairy crabs is light blue, and the blood of an arthropod called horseshoe crabs is blue. The blood of mussels and snails is also light blue. Snail's blood is white, a bit like milk. There is a kind of "white blood fish" in Antarctic waters. Its blood contains neither hemoglobin nor other substances brought by oxygen, and even no blood cells, so its blood is colorless. There are more than a dozen precious fish in the sea near the South Pole, and their blood is colorless. What is even more peculiar is a fan worm that lives on rocks at the bottom of the sea. Its blood can actually change color, turn green for a while and turn red for a while.