Pelicaniformes is an order of water birds found throughout the world. There are over 65 species divided among six families. The characteristics of the order include a bill pouch, webbed feet and advanced air sacs. Pelicaniformes are the only birds that have weeping between all four toes. The most recognizable feature for the order is the pouch in the bill known as a gular sac. Although most extreme in the pelicans it is also present in the other members.
The classification of the order has recently been under review.genetic evidence places the six species of true pelicans in an order with the Hamerkopf and Shoebill. The other families are grouped together in the order Suliformes. It is believed that the common characteristics are a result of convergent evolution and not a common ancestor. Both the American Ornithological Union and the International Ornithological Union have adopted this classification, however, both the IUCN and IISIS continue to use the older classification.
The classification of the order has recently been under review.genetic evidence places the six species of true pelicans in an order with the Hamerkopf and Shoebill. The other families are grouped together in the order Suliformes. It is believed that the common characteristics are a result of convergent evolution and not a common ancestor. Both the American Ornithological Union and the International Ornithological Union have adopted this classification, however, both the IUCN and IISIS continue to use the older classification.
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