Why is a pelican’s mouth so big?

Pelicans have large pouches, also called throat sacs, attached to their mouths to help them catch fish. They use their pouches in the same way that fishermen use nets to catch fish. When a pelican is hungry, it opens its mouth and dunks its pouch underwater to scoop up fish — along with enough water to fill two toilet bowls! Even cooler, the pouch is very sensitive and helps a pelican know when fish are nearby based solely on touch. Once a pelican scoops up a fish in its pouch, it opens its bill and slowly squeezes the water from its pouch while keeping the fish inside. Then, the pelican swallows its meal whole.