Using an electrocardiogram machine attached with suction cups to the body of a 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 (30 meters) long and weigh 200 tons, lowers its heart rate to as little as two beats per minute as it lunges under the ocean surface for food, researchers said. The maximum heart rate they recorded was 37 beats per minute after it returned to the surface from a foraging dive. The larger the animal, the lower the heart rate, minimizing the amount of work the heart does while distributing blood around the body.