The key to bubble-net feeding: how humpback whale morphology functionally differs from other baleen whales

Maneuverability in cetaceans is facilitated by pectoral flippers, flukes and spinal flexibility, features that are pronounced in humpback whales (Megaptera novaeangliae). Humpback whales exhibit several foraging tactics requiring high maneuverability not seen in other baleen whales, including bubble-net feeding. We hypothesized that the significant lift force produced by the humpback whale's uniquely large pectoral flippers will result in them being the only species observed executing the tight, high-speed, sustained turns characteristic of solitary bubble-net feeding. To test this hypothesis, we used a combination of inertial sensor tag data and unoccupied aerial systems (UAS; drone) photogrammetry to quantify the turning performance of solitary bubble-net feeding humpback whales, and compared this to similar data from six other mysticete species. We found that solitary bubble-net feeding humpback whales exhibited centripetal accelerations (0.46 m s-2) that exceeded the upper limit quantified in comparable turns by all six other mysticetes. This enhanced turning performance can be attributed to a substantial lift force generated by the humpback whale's pectoral flippers (7800±85 N), which contributes to centripetal acceleration and facilitates faster roll rates, allowing humpback whales to more quickly bank inwards and utilize their spinal flexibility to decrease their turning radius. Our findings demonstrate how humpback whales are uniquely adapted to exploit prey patches that might otherwise be insufficient for capture by animals of such a large size.