Distinctive features of pelicans are their large beaks and the bag of skin called gular pouch, which can expand and contract. The lower mandible [the bottom half of its bill] is a stable frame for the pouch.
Bill and pouch of pelicans play an important role in feeding; they serve to scoop up fish from the water. The stretchy pouch under the beak can hold several liters. As the pelican pushes its bill underwater, the lower bill bows out and the pouch fills with water and fish. As the bird lifts its head, the pouch contracts, forcing out the water but retaining the fish which are swallowed whole.
The massive, broad and long bill of the great white pelican is mostly bluish grey. It has a central red stripe, reddish maxilla edges [maxilla, top half of a pelican’s bill], and a cream-yellow to yolk-yellow gular pouch. The upper bill ends in a small, red hook, which is used for gripping slippery food items.