Octopuses Have Three Hearts and Blue Blood

 

Octopuses Have Three Hearts and Blue Blood

Yes — and two of their hearts stop beating when they swim.

Octopuses are some of the most alien-like creatures on Earth. From shape-shifting to problem-solving, they’ve amazed scientists for decades. But one of their strangest facts lies inside them — in their hearts.


Three Hearts? How Does That Work?

An octopus has:

  • Two branchial hearts: These pump blood to the gills, where it picks up oxygen.


  • One systemic heart: This pumps the oxygenated blood to the rest of the body.

Here’s the wild part:
When the octopus swims, its main heart stops beating.
That’s why octopuses prefer crawling over swimming — it’s less tiring.


Why Blue Blood?

Most animals, including humans, have red blood because of hemoglobin, which contains iron.
Octopuses use a copper-based molecule called hemocyanin, which turns their blood blue.

Why copper?

  • Hemocyanin is more efficient than hemoglobin in cold, low-oxygen environments — like the deep sea.


Quick Recap:

  • 3 hearts: 2 for the gills, 1 for the body.

  • Blue blood: Due to copper, not iron.

  • Main heart stops when swimming — making octopuses surprisingly slow and energy-conscious swimmers.


Conclusion

An animal with three hearts, blue blood, and the ability to change shape?
The octopus might just be the closest thing we have to a real-life alien.


Follow along for more facts that redefine your understanding of the natural world — only on FactSpire.

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