Octopuses possess three hearts: two branchial hearts pump blood to the gills and one systemic heart circulates oxygenated blood through the rest of the body.
Overview
The octopus circulatory system includes two smaller branchial hearts that drive blood through each gill for oxygenation and a larger systemic heart that pumps oxygen-rich blood to tissues and organs.
How the Three Hearts Work
Deoxygenated blood is collected and sent by the branchial hearts through the gills where it becomes oxygenated. The systemic heart then receives that oxygenated blood and distributes it throughout the body.
Why One Heart Stops When Swimming
When an octopus swims, the systemic heart temporarily stops beating, reducing oxygen delivery and making sustained swimming energetically costly, which helps explain why octopuses prefer crawling to swimming when possible.
Biological Significance
This cardiovascular arrangement supports the octopus's active lifestyle and blue, copper-based blood chemistry and reflects adaptations to varying oxygen demands in different behaviours and environments.
Quick Facts
- Hearts: two branchial hearts; one systemic heart
- Function of branchial hearts: pump blood to gills for oxygenation
- Function of systemic heart: pump oxygenated blood to body; pauses during swimming
- Related feature: blue blood uses hemocyanin to carry oxygen