Curious Daily
Most animals get by with one heart. The octopus has three.
Two of the hearts pump blood through the gills, where it picks up oxygen. The third pumps that oxygen-rich blood around the rest of the body.
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Here is the strange part. When an octopus swims, the main heart that supplies the body stops beating.
That makes swimming tiring, which is one reason octopuses usually prefer to crawl along the sea floor instead.
