The boobies and gannets (family Sulidae) comprise nine species of large birds with straight, sharp bills and long wedge-shaped tails. Also characteristic are the short, stout legs with four toes connected by webs. They have a small bare area on the throat and naked skin around the eye. The family inhabits chiefly the warmer seas but is also to be found in the temperate zones.

The northern gannet or solan goose, Sula bassana, with white plumage and black wingtips, is the size of a goose. It nests in large colonies on the cliffs of the North Atlantic coasts and is only found inland if forced there by storms. In winter it ranges south to the western Mediterranean and the southern states on the Atlantic seaboard of the USA. It cruises above the water's surface in gliding flight, flapping its wings occasionally, but when it sights a shoal of fish, its main food, it plummets down with its beak stretched forward. It swims rapidly underwater using its feet and half-opened wings and can dive to depths of 60 ft and more. The plumage is the same in both sexes and the young are brown, dappled in a lighter shade. Gannets and boobies have air sacs under the skin which help to soften the impact as the bird, diving from a height of 40-60 feet, hits the water. These sacs also occur in pelicans.