Compare your heart rate to an octopus's three hearts — and discover what happens during swimming.
Enter your resting heart rate to see how you compare to the octopus's three-heart system.
Unlike your single heart, an octopus has three:
The systemic heart beats at around 30–50 BPM at rest. When an octopus swims (jet propulsion through its siphon), this main heart actually stops beating — which is why octopuses prefer crawling to swimming and tire very quickly when they do swim.
Octopus blood (hemocyanin) is less efficient than human blood (hemoglobin) at carrying oxygen. Three hearts compensate by providing more pumping force at two different stages of the circulation loop.