Digestive system of humpback whales Digestive system of humpback whales The digestive system of humpback whales ("Megaptera novaeangliae") is adapted to digest tiny crustaceans such as krill, plankton, and small fish (including herring and mackerel) which the whale filters from the ocean using its baleen, a sieve-like structure in the upper jaw. Humpback whales belong to the parvorder baleen whales, which are carnivorous, seasonal feeders. The baleen, a sieve-like structure in the upper jaw made of keratin, is used to filter plankton, among other food sources, from the water. Ventral grooves are expandable concave furrows that line a whale's throat and have the peculiarity of
Baleen whale of the world, necessitating more efficiency traveling over long distances between widely distributed prey sources which also resulted in a lower metabolic rate, and feeding on baitballs. A 2017 analysis of body size based on data from the fossil record and modern mysticetes indicates that the evolution of gigantism in baleen whales is a recent phenomenon, estimated to have occurred within the past 3.1 Ma. Before 4.5 million years ago, few mysticetes exceeded 10 meters (33 feet) in length; the two largest miocene species were less than 13 m in length. The initial evolution of baleen and filter feeding long