MONTEREY, Calif. — One-hundred feet long – 400,000 pounds – and about as gentle as a giant can get.

The elusive blue whale is as massive as it is majestic, but it’s also a bit mysterious. For the first time, scientists managed to record its heartbeat, and they may have found out why the gigantic creature hasn’t grown any larger.

Researchers from Stanford University, who were studying the hearts of emperor penguins and captive whales, decided to set their sights on a much bigger catch. They found a blue whale in California’s Monterey Bay – attached a sensor pack near its left flipper with suction cups – and started recording.

They were stunned by the numbers.

Blue whale heart
A young visitor to Te Papa Museum poses for a photo inside a life-size replica of Blue Whale heart in Wellington, New Zealand, Friday, Sept. 28, 2018. (AP Photo/Mark Baker)
AP

The blue whale’s heart rate peaks between 25 and 37 beats per minute when it surfaces to breathe – then its pulse plummets to two beats per minute when it dives for food. That’s about 50 percent lower than the researchers predicted. They say the blue whale’s heart is working at its limit.

By comparison, a healthy human heart beats about 60 times per minute at rest, and it beats much faster during exercise or under stress.

“Animals that are operating at physiological extremes can help us understand biological limits to size,” said Jeremy Goldbogen, assistant professor of biology at Stanford.

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