Blue Whale Hearts May Beat Only Twice a Minute During a Dive

Blue whales have a flair for paradox. They live in water but breathe air. They’re enormous — the biggest creatures that have ever lived, as far as anyone knows — but subsist almost entirely on tiny krill. And as new research reveals, even the animal’s dunk tank-size heart jumps between extremes. In a study published Monday in the Proceedings of the National Academy of Sciences, a team of researchers for the first time attached an electrocardiogram tag to a free-diving blue whale to trace its ...