Which animals have multiple hearts?

Did you know that some animals have more than one heart?

The latest edition of ThinkTok in "24 Oras" discussed the different kinds of hearts in the animal kingdom.

The octopus has three hearts: one pumps blood to the rest of the body, while the other two pumps blood to the gills where it mixes with oxygen.

The hagfish has four: the main or branchial heart pumps blood to the rest of the body, just like the octopus, while the rest serves as accessory pumps.

Starfish, meanwhile, has no heart at all. It doesn't need one, because it doesn't have blood. What it has is cilia—hair-like structures which supply seawater into its body.

Other animals have huge hearts, especially if they have big bodies: cows have hearts the size of a human skull, while the blue whale has the biggest heart among all living organisms.

For more science trivia, watch the episode below: 

—MGP, GMA News