An octopus keeps three hearts
Two branchial hearts pump blood through the gills. A third, the systemic heart, pumps it through the body. During jet swimming the systemic heart pauses.
Established2 min read
Cephalopod blood uses hemocyanin, a copper protein, which is why it is blue when oxygenated and why it carries oxygen less willingly than our hemoglobin. Two hearts sit at the gills and push blood through them. The systemic heart takes the oxygenated blood and drives it onward.
When an octopus swims by jet propulsion, the systemic heart stops, and the animal tires quickly. Crawling is the economical gait. The anatomy and the behaviour match: a sprinter's circulation, a crawler's way of life.
Caveats
- The pause during swimming is the standard account from cephalopod physiology. It is not a claim that the animal faints.
- Not every detail of nutrient exchange is settled. The count of hearts is.
Sources
- 1Wells M. J.. Octopus: Physiology and Behaviour of an Advanced Invertebrate. Chapman and Hall, 1978.