Emus are sexually dimorphic (with two distinct gender forms) but not easily distinguished. Males are smaller than females. Both have dark gray-brown feathers and a whitish ruff at the base of their neck. The plumage on their rudimentary wings is loose and shaggy because, unlike most birds, their feathers lack the small barbules that hold them together. They have a black bill, and the skin of their head and throat is blue while their long legs are dark gray with three toes. Their eyes are reddish-brown.