Imagine a dozen humpback whales all rising to the surface at the same time, mouths agape. This is what happens during this remarkable cooperative feeding behavior.
First, a whale will find a school of small fish. Humpbacks have baleen—a sort of strainer—in their mouths rather than teeth, so they can only eat tiny fish and small shrimp-like creatures known as krill, which are abundant in Alaska waters in the summer dueto the long days and plentiful nutrients in the water that support the krill population.
The group of whales herds under the school of fish, releasing bubbles to confuse the fish and bunch them together. This ring of bubbles is visible on the water before the whales surface. Then, as one, the whales hurdle themselves up, mouths agape at angles greater than 45 degrees. The lower jaw distends like that of a bullfrog in full song. In this way a whale collects a huge mouthful of water, then spits it out, straining it through its baleen. And of course, the food is caught in the baleen. Often the whales will do this feeding over and over.