Scientists measure the heart rate of the blue whale

Blue whale

Scientists for the first time have measured the heart rate of the world’s largest creature.

The blue whale, which can reach up to 100 feet in length and weighs 200 tons, is the largest mammal to have ever lived and possesses the largest heart of any living creature — around 180 kg. It lowers its heart rate to as little as two beats per minute as it plunges under the ocean surface for food. Its highest heart rate — between 25 and 37 beats per minute — occurs when it returns to the surface to restore oxygen levels.

These extremes suggest that the blue whale’s heart is “working at its limit”. A more robust cardiovascular system is not likely, and the research may explain why no species on Earth has grown bigger than the blue whale, since the energy needs of a larger body might surpass what’s biologically possible for a heart to accommodate.