This behavior is not instinctual, it is learned.[1] Not every population of humpbacks know how to bubble net feed, according to some studies.[5] After observing different populations it is apparent which whales know how to create a bubble net and which do not.[5] To be successful, they must learn the method. Humpback whales use vocalizations to communicate to one another and effectively and efficiently execute the bubble net so they all can feed.[5] 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.[5] One whale will typically begin to exhale out of their blowhole beneath the surface at the school of fish to begin the process.[5] 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.[5] The size of the net created can range from three to thirty meters in diameter.[7] One whale will sound a feeding call, at which point all whales simultaneously swim upwards with mouths open to feed on the trapped fish.[5] 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.[5] Humpback whales have 14 to 35 throat grooves that run from the top of the chin all the way down to the navel.[3] These grooves allow the mouth to expand.[4] When they swallow they stream the water out through their baleen as they ingest the fish.[4] The fish that they ingest are also a source of hydration for them.[4] Bubble netting is an advanced and necessary feeding method developed by humpback whales to feed multiple mouths at one time.