Blue whales can slow their hearts to a near stop while diving for food, study shows

Blue whales, the largest creatures known to have lived on Earth, can slow their heart rates to as low as 2 beats per minute while diving for food, a new study reveals.

Researchers from Stanford University attached an electrocardiogram sensor to a 72-foot male blue whale in California’s Monterey Bay to collect the data, ScienceAlert reports.

They recorded its heart rate for nine hours as the whale, which is at least 15 years old, repeatedly dove to feed and resurfaced, LiveScience reports.

It was the first recording of a blue whale’s heart rate, a Stanford University release says.

The study, published Monday in Proceedings of the National Academy of Sciences, found the whale’s heart rate ranged from nearly 40 beats per minute on the surface while recovering from a dive to as low as 2 to 8 beats per minute while diving.

Lowering its heart rate allows the whale to stay underwater longer as it feeds on tiny krill and plankton at the bottom of the sea, according to the report.

Normal resting human heart rates range from 60 to 100 beats per minute, rising to up to 200 beats per minute during physical exertion, ScienceAlert reported.

The heart of one beached blue whale found in 2015 weighed 400 pounds and appeared to be about the size of a golf cart, LiveScience reported. Blue whales can reach up to 100 feet long and weigh as much as 200 tons.

“The biology of the blue whale has long fascinated physiologists because of the animal’s extreme size,” the study says.

Researchers discovered that recovering from a dive taxes the blue whale’s heart nearly to its limit, LiveScience reported. It may help explain why blue whales are Earth’s largest known creatures.

“Animals that are operating at physiological extremes can help us understand biological limits to size,” said lead study author Jeremy Goldbogen, an assistant professor at Stanford University, in the university’s release.

In order to record the whale’s heartbeats, researchers attached a plastic pod with four suction cups to one of its flippers, the release says.

“I honestly thought it was a long shot because we had to get so many things right: finding a blue whale, getting the tag in just the right location on the whale, good contact with the whale’s skin and, of course, making sure the tag is working and recording data,” Goldbogen said.

This story was originally published November 26, 2019 at 9:35 AM.