Biology
What gives octopus blood its unique color?
Quick fact
Octopus blood is blue because it uses hemocyanin instead of haemoglobin.
Why this is interesting
Humans have red blood, but octopuses carry oxygen using a molecule that contains copper.
Read the full explanation
Understanding What gives octopus blood its unique color?
Hemocyanin contains copper atoms that bind with oxygen, creating a blue colour.
A deeper explanation
Copper-based oxygen transport works better than iron-based systems in cold, low-oxygen environments.