An octopus has three hearts — and two of them stop beating every time it swims.

That's not a metaphor. When an octopus swims, the two hearts that pump blood to its gills literally shut down. This is why octopuses prefer crawling along the seafloor: swimming exhausts them.

Oh, and their blood is blue. It uses copper instead of iron to carry oxygen, which works better in cold, low-oxygen water — but makes swimming even more tiring.

So the next time someone says they're "putting their heart into it" — remind them an octopus puts in three. And still gets winded walking to the fridge. 🫠

💬 Which fact surprised you more — the three hearts , or the blue blood?
@science