Octopus Hearts: A Unique Survival Challenge

Octopuses have three hearts and blue blood. Two hearts pump blood to their gills

while the third sends it to the rest of their body. Their blood is blue because it contains

copper instead of iron like ours. But here is the wildest part: when an octopus swims,

the heart that delivers blood to the body actually stops beating. That is why they prefer crawling

along the ocean floor rather than swimming. These incredible creatures literally

have to choose between moving efficiently and staying alive.