1. Copper-containing proteins found in the blood of certain arthropods and mollusks that function similarly to hemoglobin in carrying oxygen throughout the body.
Usage: plural form; technical/scientific term; used in biology and biochemistry

Examples

• Hemocyanins are the oxygen-transport proteins in the blood of horseshoe crabs and octopuses.
• Unlike hemoglobin, hemocyanins contain copper atoms rather than iron.
• The blue color of octopus blood comes from the hemocyanins dissolved in it.
• Scientists study hemocyanins to understand how different organisms evolved different respiratory proteins.
• Hemocyanins are less efficient at oxygen transport than hemoglobin in cold temperatures.