💡 Trivia The 3 Hearts, 9 Brains, and Blue Blood of the Octopus

[Icebucks23]

Octopuses possess one of the most alien physiological systems on Earth: 3 hearts, 9 brains, and blue blood.

• 9 Brains: A central donut-shaped brain encircles the esophagus, while two-thirds of the octopus’s neurons are distributed throughout its eight arms. Each arm functions as an independent "mini-brain" that can touch, taste, and navigate without waiting for signals from the central head.
• 3 Hearts: Two branchial hearts pump blood exclusively through the gills to pick up oxygen, while a central systemic heart circulates blood to the rest of the body.
• Blue Blood: Instead of iron-based hemoglobin (which turns human blood red), octopuses rely on copper-based hemocyanin to transport oxygen in cold, low-oxygen ocean depths.

© Ocean Science Institute