These sophisticated invertebrates have three hearts! One circulates blood throughout the body, while the other two oxygenate blood through their gills.
Squid
Squids also have three hearts. Amazingly, their hearts will continue to beat for hours after being removed from the body!
Hagfish
These primitive jawless fish have a unique four-chambered heart with three other hearts that help maintain blood pressure and circulation.
Earthworm
While not technically having true hearts, earthworms have a network of pulsating vessels called aortas that act like hearts.
Shrimp
Though not quite multiple, shrimp have a unique one-chambered heart with three openings for efficient underwater circulation.
Cockroach
Some cockroach species, such as the Pacific beetle, have several small hearts in their bodies. Despite their small size, these pulse tubes effectively help circulation.
Sea cucumber
Sea cucumbers hold the record for most hearts, with up to 30 scattered throughout the body to independently pump blood.