Sulidae

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. The 10 species in this family are often considered congeneric in older sources, placing all in the genus Sula. However, Sula (true boobies) and Morus (gannets) can be distinguished via morphological, behavioral, and DNA sequence characters. Abbott's booby (Papasula) is given its own genus, as it stands apart from both in these respects. It appears to be a distinct and ancient lineage, maybe closer to the gannets than to the true boobies.

==Description== thumb|left|Blue-footed booby (Sula nebouxii) with distinctive colouring and bill. thumb|left|Northern gannet (Morus bassanus) preparing to land Sulids measure about in length and have a wingspan around . They have long, narrow, and pointed wings, and a quite long, graduated, and rather lozenge-shaped tail whose outer feathers are shorter than the central ones. Their flight muscles are rather small to allow for the small cross-section required for plunge-diving, as an adaptive trade-off relative to some sacrifice in flight performance. Consequently, they are very streamlined, reducing drag, so their bodies are "torpedo-shaped" and somewhat flat.