What volunteers had failed to realize was that the comparisons they were making when the chips were in their heads were not the comparisons they would make when the chips were in their mouths.
In coordinated groups, the animals first cornered and then herded a massive school of herring, blowing bubbles around them to confuse the fish and make them swim tighter, until, surging through the middle of the school with mouths agape, the humpbacks boiled to the surface in a feeding frenzy.