Octopus Hearts and Blue Blood Facts

Octopuses literally have three hearts and blue blood running through their bodies. I discovered this

mind-blowing fact while researching marine biology, and it completely changed how I see

these incredible creatures. Two hearts pump blood to their gills, while the third

pumps blood to the rest of their body. The blue color comes from copper-based hemocyanin instead

of iron like humans have. What absolutely floors me is that the main heart actually

stops beating when they swim, which is why octopuses prefer crawling along the ocean

floor to avoid exhaustion.