ZAP’S FACTS!
SEA LIFE

An octopus has three hearts and blue blood.

Two hearts pump blood to the gills, one to the body - and the main one stops when they swim.

2 min read
An orange octopus grins, holding two cartoon hearts with lightning bolts, surrounded by blue droplets on a bright blue…
THE FULL STORY

Most animals get by with a single heart. An octopus has three. Two of them - called branchial hearts - sit next to the gills and push blood through them to pick up oxygen. The third, bigger systemic heart then pumps that oxygen-rich blood around the rest of the body.

Here’s the really odd part: the systemic heart slows right down - and can even pause - when an octopus jets through the water. That’s exhausting, which is one reason octopuses usually prefer to crawl along the seabed rather than jet through open water.

And the blood itself isn’t red - it’s blue. Instead of iron-based hemoglobin (which makes our blood red), octopus blood uses a copper-based molecule called hemocyanin. It carries oxygen really well in cold, low-oxygen deep water, and it turns blue when it does.

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