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 minke whales, catching nearly 7,000; to a far lesser extent, they also caught fin whales. Animal-rights activist groups, such as the Greenpeace, object to Japan's scientific whaling, with some calling it a substitute for commercial whaling. In 2014, the International Court of Justice (the UN judicial branch) banned the taking of whales for any purpose in the Southern Ocean Whale Sanctuary; however, Japan refuses to stop whaling and has only promised to cut their annual catches by a third (around 300 whales per year). Baleen whales can also be affected by humans in more indirect ways. For species like the