There are humpback whales doing a practice called bubble feeding which has only been observed in Western Alaska. A pod of humpback whales (about a dozen) work together to capture the krill and small fish they live on. First they sight a school of herring. One whale encircles the herring with a ring of bubbles while the pod swims below them with their mouths open. Meanwhile, a group leader gives auditory signals you can hear through an underwater microphone (hydrophone). When the "go" signal sounds the whales all swim towards the surface, mouths open, until the food trapped within the circle of bubbles gets to the surface of the water. All the whales, each of them 30 tons and 50 feet long, simultaneously break through the layer of food concentrated on the surface with their mouths fully open. It's an incredible sight to say the least.