SAN DIEGO — Researchers from Stanford and UC San Diego have achieved a difficult breakthrough, making the first recordings of a blue whale’s beating heart while the animal swam in the wild along the California coast.

The achievement was first reported on Monday in the Proceedings of the National Academy of Sciences.

The feat occurred in Monterey Bay, where Stanford scientists attached a small recording device to the animal.

“Four suction cups had secured the sensor-packed tag near the whale’s left flipper, where it recorded the animal’s heart rate through electrodes embedded in the center of the two suction feet,” Stanford said in a news release.

The sensor package later floated to the ocean’s surface, where the data was captured and reviewed by a team that included Paul Ponganis, a research physiologist at UC San Diego’s Scripps Institution of Oceanography.

“This study is significant because we have developed a technique to record the electrocardiogram and heart rate of the largest animal that has ever lived on the earth,” Ponganis said in a statement.

“The heart rate data are consistent with allometric predictions based on body mass and the heart rate data confirm anatomical-biomechanical models of vascular function in such large animals.”

Blue whales are typically 80 to 100 feet in length, and they can weigh up to 441,000 pounds. Treehugger.com says that the heart of these whales is 5 feet long, 4 feet wide and 5 feet tall and weighs around 400 pounds.