Pelecaniformes is the scientific name for medium to large, aquatic birds. Pelecaniformes are made up of three families. This includes: Phaethontidae or tropicbirds, Sulidae which includes boobies and gannets, Phalacrocoracidae which are cormorants and shags, Anhingidae, Pelecanidae or pelicans, and Fregatidae also know as frigate birds. There's around 67 species in the Pelecaniformes phylum.

Pelecaniformes are distinguished from other birds. They have webbed feet, a bare throat patch, and they breathe through their mouths because they have dysfunctional slits. Pelecaniformes birds can be located worldwide, primarily in coastal and marine zones. These birds inhabit marine and island waters. Pelecaniformes mostly feed on fish and squid. Also, this bird has been known to prey on mollusks and crustaceans. 

There are about one- third of Pelecaniformes birds that may have come close to extinction. These problems include polluted water and loss of habitat for nesting.  Their nesting is colonial. Some nesting site can be found anywhere from in a tree or bush or on a cliff. However there are many Pelecaniformes birds still living today.