hemocyanin
/ˌhiməˈsaɪənɪn/
noun
- A blue, copper-containing protein in the blood of some animals, such as mollusks and arthropods, that carries oxygen.
- The blue color of horseshoe crab blood comes from hemocyanin.
- Unlike humans, octopuses have hemocyanin instead of hemoglobin.
- Crabs and lobsters use hemocyanin to transport oxygen in their blood.