Sula sula Linnaeus, 1766

Its external nostrils are closed to allow for plunge-diving, but it has developed secondary nostrils beside the mouth which are automatically covered by flaps when it plunges. The skin around its face is generally bare. The eyes are beside the bill, face forward, and have very pale irises. The wings are long, pointed, and situated fairly far back on the body.he legs are short and strong, and the feet are large and totipalmate The plumage is molted continuously so as not to hinder the bird's flight capability at any one time, however, molt is suspended during breeding. Feathers are renewed 1 to 2 times yearly. Sula sula lacks a brood patch because it would interfere with streamlining and insulation. There are several morphs of this bird, often making it difficult to identify without noting the color of its feet. The morphs are: the white-tailed brown morph, the white headed and white tailed brown morph, the white morph (which has black on its wings), the black-tailed white morph (found on the Galapagos Islands), and the golden white morph (found on the Christmas Islands).