An octopus has two branchial hearts that pump blood through its gills, where oxygen is picked up. Its third, systemic heart sends oxygen-rich blood to the rest of the body.
Octopus blood uses a copper-containing protein called hemocyanin to transport oxygen. It can be especially effective in cold, low-oxygen environments, and makes their blood appear blue.
The systemic heart slows dramatically or may temporarily stop when the octopus swims. That helps explain why octopuses often prefer crawling along the sea floor.
Quick curiosities
- Two hearts serve the gills.
- One heart serves the rest of the body.
- Their oxygen-carrying blood pigment is copper-based.
Keep wondering
- What is the smartest thing an octopus can do?
- Which animals have unusual hearts?
- Why is octopus blood blue?