Why do whales explode into giant feeding frenzies together?

Humpback whales burst upward in groups because teamwork helps them catch small fish that would otherwise dart away. Several whales herd a school from below with rising bubbles and sound, then surface at the same moment with open mouths, scooping fish and seawater together.

The lovely part is that the bubbles act like a pretend wall. The fish crowd away from it, even though it is only air in water. Then the whales strain the mouthful through baleen, keeping dinner while the sea pours back out.