Morus Papasula Sula Enkurosulidae Kashin, 1977 Pseudosulidae Harrison, 1975[1][2] The bird family Sulidae comprises the gannets and boobies.

Collectively called sulids, they are medium-large coastal seabirds that plunge-dive for fish and similar prey.

However, Sula (true boobies) and Morus (gannets) can be readily distinguished by morphological, behavioral, and DNA sequence characters.

Unlike their relatives (the darters and cormorants), sulids have a well-developed preen gland whose waxy secretions they spread on their feathers for waterproofing and pest control.

These birds are not truly pelagic seabirds like the related Procellariiformes, and usually stay rather close to the coasts, but the abundant colonies of sulids that exist on many Pacific islands suggest that they are not infrequently blown away from their home range by storms, and can wander for long distances in search of a safe place to land if need be.

If prey manages to escape the diving birds at first, they may give chase using their legs and wings for underwater swimming.

Males examine the colony area in flight and then pick a nest site, which they defend by fighting and territorial displays.

Their display behavior is characteristic, though not as diverse as the numerous variations found among the cormorants; it typically includes the male shaking his head.

The eggs are unmarked (but may become stained by debris in the nest), whitish, pale blue, green, or pink, and have a coating that resembles lime.

Both sexes incubate; like their relatives, they do not have brood patches, but their feet become vascularized and hot, and the birds place the eggs under the webs.

[5] Sulids are related to a number of other aquatic birds, which all lack external nostrils and a brood patch, but have all four toes webbed and a gular sac.

In recognition of this, the Sulae have been proposed for separation in a new order Phalacrocoraciformes, which also includes the frigatebirds (Fregatidae), as well as one or more prehistoric lineages that are entirely extinct today.

The initial evolutionary radiation formed a number of genera that are now completely extinct, such as the freshwater Masillastega (which, as noted above, might not have been a modern-type sulid) or the bizarre Rhamphastosula (which had a bill shaped like an aracari's).

Like the other Phalacrocoraciformes, the sulids originated probably in the general region of the Atlantic or western Tethys Sea – probably the latter rather than the former, given that their earliest fossils are abundant in Europe, but absent from the well-studied contemporary American deposits.