High-tech tag helps scientists measure blue whale's heart rate

Nov. 26 (UPI) -- Scientists have for the first time measured the heart rate of the world's largest animal, the blue whale. Researchers accomplished the feat -- reported this week in the journal PNAS -- with a retrievable tag packed full of sensors.

Scientists previously tested their tag on captive whales, but researchers weren't sure they were going to be able to successfully attach to the underside of a blue whale in the wild.

"We had no idea that this would work and we were skeptical even when we saw the initial data. With a very keen eye, Paul Ponganis -- our collaborator from the Scripps Institution of Oceanography -- found the first heart beats in the data," lead study author Jeremy Goldbogen, assistant professor of biology at Stanford University, said in a news release. "There were a lot of high fives and victory laps around the lab."

The tag's data suggests the blue whale's heart is working at maximum capacity, which may explain why no animal has evolved to outgrow the blue whale. The massive marine mammal is likely the largest body the heart can support.

According to the newly recorded data, the whale's heart slowed to just a few beats per minute during deep dives. When the whale surfaced to breathe and recover, its heart rate accelerated to 40 beats per minute. Researchers didn't expect the heart's slowest rate to be so slow, nor did they expect the heart rate's peak to be so fast.

The observations could help scientists better understand how the planet's largest animals evolve the necessary physiology to support such extreme dimensions.

Researchers now hope to boost the tag's technology by adding an accelerometer and repeating the feat.

"A lot of what we do involves new technology and a lot of it relies on new ideas, new methods and new approaches," said David Cade, a recent graduate of the Goldbogen Lab. "We're always looking to push the boundaries of how we can learn about these animals."