There's actually only 1 well known animal that has 5 hearts, which is the earthworm.
Earthworms, however don't have traditional hearts, but instead earthworms have 5 pairs of aortic arches that are often called hearts, which wrap around the earthworms esophagus and acts as pumps to circulate the blood through the earthworms bodies.
Other animals that have more than one heart or multiple hearts are octopuses and squids and hagfish.
Hagfish have 4 hears, with 1 main heart and 3 accessory pumps for their circulatory system.
And octopuses and squids have 3 hearts, with one main heart and two gill hearts.
Also the animal that has the largest heart is the blue whale.
The blue whale has a massive sized heart and the largest heart in the animal kingdom.
A blue whales heart is roughly the size of a small car and weighs around 400 to 440 pounds.
The heart of a blue whale measures around 5 feet long, 4 feet wide and 5 feet tall.
And the aorta of the blue whales heart is also so incredibly large that a human could theoretically crawl through it without issues.
The blue whales heart also pumps around 60 gallons of blood with every beat of it's heart.
And during a deep dive, the blue whale, heart rate also slows down to just 2 beats to 10 beats per minute, to allow the blue whale to conserve oxygen.
I was surprised to learn the size of a blue whales heart in school when a scientists showed up to our school years ago.
It really amazed me then and still amazes me to this day that a blue whale can have such a massive and large heart.