Animals - Animal types and traits - Octopuses - Octopus anatomy - Cephalopods
Why do octopuses have three hearts?
Correct!
In octopuses, two branchial hearts pump oxygen-poor blood to the gills. There it is enriched with oxygen before a third, systemic heart sends the blood through the rest of the body.
This anatomy fits their circulatory system. Octopuses also have blue blood because they use copper-containing hemocyanin to carry oxygen, rather than iron-containing hemoglobin. During active swimming, the systemic heart can slow or briefly stop, which is one reason crawling is often less demanding for octopuses.
