Humpback whale
Feeding

Humpback whales feed from spring to fall. They are generalist feeders, their main food items being krill, copepods, other plankton and small schooling fish. The most common krill species eaten in the southern hemisphere is the Antarctic krill. Further north, the northern krill and various species of Euphausia and Thysanoessa are consumed. Fish prey include herring, capelin, sand lances and Atlantic mackerel. Like other rorquals, humpbacks are "gulp feeders", swallowing prey in bulk, while right whales and bowhead whales are skimmers. The whale increases its mouth gape by expanding the grooves. Water is pushed out through the baleen. In the southern hemisphere, humpbacks have been recorded foraging in large compact gatherings numbering up to 200 individuals.

Humpbacks hunt their prey with bubble-nets. A group swims in a shrinking circle while blowing air from their blowholes, capturing the prey above them in a cylinder of bubbles. They may dive up to 20 m (70 ft) performing this technique. Bubble-netting comes in two main forms; upward spirals and double loops. Upward spirals involve the whales blowing air from their blowhole continuously as they circle towards the surface, creating a spiral of bubbles. Double loops consist of a deep, long loop of bubbles that herds the prey, followed by slapping the surface and then a smaller loop that prepares the final capture. Combinations of spiraling and looping have been recorded. After the humpbacks create the "nets", the whales swim into them with their mouths gaping and ready to swallow.

Using network-based diffusion analysis, one study argued that whales learned lobtailing from other whales in the group over 27 years in response to a change in primary prey. The tubercles on the flippers stall the angle of attack, which both maximizes lift and minimizes drag (see tubercle effect). This, along with the shape of the flippers, allows the whales to make the abrupt turns necessary during bubble-feeding.
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