Flamingoes have been classed alternately with the Ducks and with the Storks, but recent writers on ornithology have for the most part followed Huxley and arranged them as an intermediate and independent group.
They have a remarkable bill, covered with a soft epidermis, and bent downwards in the middle, the lower mandible very thick and practically fixed, the upper mandible much smaller and highly movable; the margins of both mandibles furnished with lamellae. Both the neck and legs are very long, and adapted, with the bill, for feeding whilst the bird stands in shallow water with the neck turned down and the head inverted, so that the lower mandible is uppermost, the lamellae at the sides of the mandibles serving to strain the food from water and mud as the head is moved from side to side. The tarsus and long bare tibia are scutellated both in front and behind ; the feet are short, the anterior toes fully webbed, the hind toe small or wanting.
The skull is desmognathous and holorhinal, basipterygoid processes are very rudimentary or wanting, nostrils pervious ; cervical vertebrae 18 or 19. The carotids are peculiar, the right is much larger than the left, and the two unite at the base of the neck. The caeca are very large. The wing is aquincubital; primaries 12; the oil-gland tufted; an aftershaft is present; there are no bare spaces at the side of the neck, and both dorsal and ventral apteria are short. The ambiens muscle is present, and the femoro-caudal absent; accessory femoro-caudal, semitendinosus and its accessory present. The deep plantar tendons unite completely, and then divide to supply the anterior toes, as in most birds with the hallux rudimentary or wanting.
The nidification is described under P. roseus. The young are hatched with a straight bill; they are covered with down and able to run.
The order consists of a single family, and the two species found in India may be kept in the typical genus Phoenicopterus. They have been separated by some writers on account of the different form of the bill.