Knob billed Duck This bird wears its crown not of feathers, but of horn. The Knob billed Duck (Sarkidiornis melanotos), also known as the Comb Duck, is one of the most unmistakable waterfowl in the world. Knob Billed Male Duck: (Sarkidiornis melanotos) or African comb duck or comb duck is a type of duck.The male is much larger than the female, and has a large black knob on the Comb Duck (Sarkidiornis melanotos) AKA Knob billed Duck