There are two families in this order, both consisting of flightless, walking birds. Other characteristics include a flat sternum, stout legs with three toes, and feathers with large after-shafts (a double feather that grows from the shaft of a body feather). The two families of Casuariiformes are Cosurety (cassowaries) and Dromiceidae (emus).

Cassowaries atand 4.5 to 5.8 feet tall and weigh from 70 to 120 pounds. They feed on fallen fruits which they eat whole. They need large areas of forest floor for sustenance. Their survival as a family may depend on the survival of tropical forests which are so threatened today. Being solitary animals, they come together only in the breeding season. All are confined to New Guinea and Australia and possess sleek, drooping, brown plumage. Their wing quills are enlarged, spike-like structures used in fighting and defense. Their three toes can also be effective weapons and the kick of a Cassowary has lethal power. They are excellent swimmers and divers, and can run at speeds of 30 mph. In all species, the head and long neck are without feathers. The head is adorned with a horny casque, while the neck is ornamented with bright blue skin. There is no sexual dimorphism, although the female is larger than the male.

The people of New Guinea have kept some of these birds in captivity in order to assure their supply. The plumes are plucked for decoration, the quills are used as nose ornament, and the whole bird may be consumed at feast times.

Inhabitants of Australia for at least 80 million years, the Emus are large, shaggy-looking birds. Their feathers hang limply from the body. The neck and legs are long but the wings are a mere 8 inches in length. Emus ingest pebbles to help the gizzard grind up food, and they often eat charcoal. Because their food supply (desert vegetation) can be quickly exhausted in their arid environment, the emu roams constantly. When food is abundant the emu stores large amounts of fat in its body.