Procellariiformes is an order of seabirds that comprises albatrosses, shearwaters, and various type of petrels. Wings are long and narrow; feet are webbed, and the hind toe is undeveloped or non-existent. Plumage is predominantly black, white and gray. They are almost exclusively pelagic (feeding in the open ocean). They distributed across the world's oceans, with the highest diversity being around New Zealand. Procellariiformes mostly nesting on remote predator-free islands. Only a single egg is laid per nesting attempt. The various species within the order have a variety of migration strategies. Many species undertake regular trans-equatorial migrations. However, no albatrosses cross the migrate across the equator because they rely on wind assisted flight.

The order has a few unifying characteristics, starting with their tubular nasal passages enclosed in one or two tubes on their straight, deeply grooved bills with hooked tips. These passages are used for smelling which helps to locate patchily distributed prey at sea and may also help locate their nests within nesting colonies. Also, they have a stomach oil stored that can be used as a food source during their long flights and also as a defense mechanism. All birds have an enlarged nasal gland at the base of the bill, above their eyes. This gland is inactive in species that don't require it; however the Procellariiformes do require its use due to their drinking of ocean water. It removes salt that forms a 5% saline solution that drips out of their nose or is forcibly ejected in some petrels. [abstracted from Wikipedia]