Ocean field note
Extra beats
Three Hearts, One Octopus
An octopus has three hearts, and one of them stops beating every time it swims.
Let's look closer
Why would an octopus's own heart stop while it's swimming?
wo of the hearts push blood through the gills to pick up oxygen, while the third pumps that blood to the rest of the body. But that third heart pauses whenever the octopus jets forward through the water, which is part of why octopuses seem to prefer crawling along the seafloor instead of swimming β it's tiring work. Their blood is even blue, colored by a copper-based substance instead of the iron that makes our blood red.
Look for this
Explorer clue
Watch a video of an octopus at an aquarium and notice how much more often it crawls with its arms than swims through open water.
Your turn to wonder
Curiosity question
If you had an extra heart, what would you want it to do?
Keep wandering
