The heart of a blue whale weighs about a half a ton, 1000 lbs. It has to be large enough to pump about 15,000 pints of blood as compared to about 8 pints in a human.
The average heart rate for a man is 72bpm. A blue whale’s heart beats six times a minute. A horse has 38bpm. A rabbit has 205bpm. A rat 420. A mouse 670. The heartbeat of a canary occurs 17 times in a second.
A rate of 1260 beats per minute was measured in a Blue-throated Hummingbird. In torpid hummingbirds, the heart rate can drop to 50-180 per minute.
A giraffe depends on it’s powerful heart that weighs up to 12kg so that it can fight the force of gravity up that long neck to the head.
Octopuses have three hearts.
Zebrafish can regenerate its heart.