Clearer, same ducks in the water and a mouth full. Humpbacks will feed on krill and various kinds of small, shoaling fish such as herring (check out the mouth) and mackerel. They may eat up to 1,400 kg (3,000 lbs.) of food a day. As the mouth closes the whale will press down with its tongue forcing all water out through baleen plates. These baleen plates hang in row from each side of the upper jaw. This traps the herring / lunch inside.