Octopuses crawl when they can swim because their cardiac systems don’t operate at full capacity. Although an octopus has three hearts, only two of them beat while they are swimming. This is because two of the hearts are used to pump blood to the octopuses’ gills, while the third heart is reserved for circulating blood to the organs only.
Since their two hearts are not pumping as much blood throughout their bodies as they would normally, octopuses can become fatigued while swimming. Crawling conserves their energy while still allowing them to travel through the water.
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