For the First Time, Scientists Record the Slow Beat of a Blue Whale's Heart
This is the first heart rate recording of any wild large whale, and the biggest one to boot: Blue whales are the largest animals ever known to have lived on Earth. And the recordings might hint at a biological limit for heart size in mammals. Based on their recordings, the researchers believe blue whales' hearts might be just about as big as they come.
Another question for the researchers concerned the whales' feeding habits. Blue whales feed by diving several hundred feet below sea level. There, they take huge gulps of water in the hopes of trapping tiny shrimp called krill in their mouths. Those trips take a lot of energy, and the research team was curious how the heart coped with that strain.
So biologists and oceanographers from California and Washington gave a 15-year-old blue whale a heart test that many people have had in their own doctor’s office. Called an electrocardiogram, or EKG, it uses electrodes stuck to the skin to measure heart activity. Once the team was close enough to a wild whale, the biologists suction-cupped the device near the whale’s flipper.