Octopuses are fascinating examples of biological engineering. Their three-heart system is a specialized adaptation that supports their high-energy lifestyle and unique copper-based blood.
Here is a detailed breakdown of how their hearts work:
1. The Two Branchial Hearts (The “Gill Hearts”)
These two smaller hearts are located at the base of each of the octopus’s two gills.
- The Function: Their sole job is to pump deoxygenated blood through the gills.
- The Process: Just as a human heart pumps blood to the lungs, these hearts push blood into the gill capillaries where waste carbon dioxide is exchanged for fresh oxygen from the seawater.
2. The One Systemic Heart (The “Main Heart”)
The systemic heart is the largest and most powerful of the three.
- The Function: Once the blood is oxygenated by the gills, it flows to the systemic heart, which then pumps it out to the rest of the body’s organs and limbs.
- The “Swimming” Quirk: Interestingly, when an octopus swims, the systemic heart stops beating. This is why octopuses prefer crawling or “walking” along the seafloor; swimming is physically exhausting because their main heart isn’t providing a steady flow of oxygenated blood during the exertion.
3. Why Three Hearts? (The Blue Blood Factor)
The need for three hearts is largely due to the chemistry of their blood.
- Hemocyanin vs. Hemoglobin: Unlike humans, who use iron-based hemoglobin (which makes blood red), octopuses use copper-based hemocyanin (which makes their blood blue).
- Efficiency: Hemocyanin is less efficient at transporting oxygen than hemoglobin. To compensate for this, the octopus needs the extra pressure provided by three separate hearts to ensure enough oxygen reaches its muscles and complex brain.
