Last updated: October 12, 2017 at 3:36 am
Hagfish (Myxini spp.) have four hearts composed of a three-chambered systematic heart assisted by three accessory pumps.
Cephalopods (octopus and squid) have three hearts composed of a systematic heart and two gill hearts sending blood to and from the gills.
Verified by Diving Almanac & Book of Records official
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Jeffrey Gallant is the Editor-in-Chief and Records Keeper of the Diving Almanac. He is also a contributing editor of DIVER Magazine, and the scientific director of the Greenland Shark and Elasmobranch Education and Research Group (GEERG). Jeffrey started diving in 1982.