Bubble net feeding

Bubble-net feeding is a unique and complex feeding behavior engaged in by Humpback whales (Megaptera novaeangliae) and Bryde's whales in Gulf of Tosa (), Japan. It is one of the few surface feeding behaviors that humpback whales are known to engage in. This type of feeding is often done in groups. The group size can range from a minimum of two or three whales participating and up to sixty at one time. Whales can also perform a similar method of surface feeding called lunge feeding but is done solo.

Humpback whales are migratory and only eat during half the year. They will typically spend the summer months (May through September) in feeding grounds with cooler waters that they return to every year. They have been documented feeding in areas such as Southeast Alaska and off the coast of Antarctica. During the other half of the year humpbacks will spend time in their breeding grounds where they do not eat at all. During their feeding season humpback whales will actively feed for up to twenty-two hours a day. They do this in order to have enough fat reserves stored in their bodies to live off of during their breeding season.

Bubble-net feeding is a cooperative feeding method used by groups of humpback whales. This behavior is not instinctual, it is learned. Not every population of humpbacks know how to bubble net feed according to some studies. After observing different populations it is apparent which whales know how to create a bubble net and which do not. They have to learn the method in order to be successful. Humpback whales use vocalizations to communicate to one another in order to effectively and efficiently execute the bubble net in order for them all to feed. As the group circles a school of small fish such as salmon, krill, or herring they use a team effort to disorient and corral the fish into a net of bubbles. One whale will typically begin to exhale out of their blowhole beneath the surface at the school of fish to begin the process. More whales will also start to blow bubbles while continuing to circle their prey. They corral the fish into a tight circle while creating a net of bubbles to surround the fish and keep them from escaping. The size of the net created can range from three to thirty meters in diameter. One whale will sound a feeding call, at which point all whales simultaneously swim upwards with mouths open to feed on the trapped fish. As the whales swim up to the surface to feed they can hold up to 15,000 gallons of sea water as they use their baleen plates to strain the water to get the maximum amount of fish they need. Humpback whales have 14 to 35 throat grooves that run from the top of the chin all the way down to the navel. These grooves allow the mouth to expand. When they swallow they blow the sea water out from their blowhole as they ingest the fish. The fish that they ingest are also a source of hydration for them. Bubble netting is an advanced and necessary feeding method developed by humpback whales to feed multiple mouths at one time.

...
Wikipedia