The world’s largest animals have been hiding something. The bodies of the giant rorqual whales—including the blue, fin and humpback—have been regularly displayed in museums, filmed by documentary makers, and harpooned by hunters. Despite this attention, no one noticed the volleyball-sized sense organ at the tips of their lower jaws. Nicholas Pyenson from the Smithsonian Institution is the first, and he thinks that the whales use this structure to coordinate the planet’s biggest mouthfuls.

The rorquals sieve tiny prey from the water with a unique hunting technique called lunge feeding. They surge forwards, open their mouths and swallow everything in front of them. This seemingly simple tactic is one of the most extreme in the animal kingdom. In one