Arwhals were a species of immense airborne mammals fondly remembered by poets of the pre-Congress era for their majestic size, luminous skin, graceful flight, and succulent taste. The Pulotu people referred to them collectively as "pulupulu-kama," or "Brother Sky," while Aetherists called them "the Great Barrier," after the tendency of vast migrating herds to disrupt and endanger the flow of air traffic. The global arwhal population was once so dense that schools routinely blocked out the sun for days, but by the time the Arwhal Preservation Act enabled, only a few dozen remained.

Arwhal hunting, initially concerned with supplying a delicacy to a niche market of royals and industrialists, leapt with the discovery in 738QE of arwhal oil, a viscous, volatile, lighter-than-air substance secreted by the animal's endochrine system. Believing that a new revolution in flight was imminent, entrepreneurs dispatched fleets of arwhalers to sieze the substance. Processed arwhals lead to the birth of oil-powered flight, making larger and heavier craft possible and eventually culminating in the armed smokeships that made massive aerial combat possible. By the time of the Gravitopolis War, arwhaling had eclipsed slaving as the most profitable industry in the world.

Eventually the dwindling arwhal population met with public sympathy, eventually culminating in the unanimous passage of the Arwhal Preservation Act at the convention of the Floating Congress. But while the act labeled the imminent extinction of the arwhals "a grave crisis" and called for something to be done, it actually took no steps to save the last lingering specimens of the species. Arwhaling continued, although in decreased demand, as newer and more efficient means of flight replaced the old oil-powered ships. Some meteromancers insisted they could save the dwindling arwhal population by alchemically synthesizing a substitute for arwhal oil if provided with enough samples; sadly, this effort lead to nothing more than an increase in research hunting to supply meteromancers. The last arwhal was killed by accident in 898QE, when it was hit by a tourist liner. The last historical remnants available of the existence of arwhals are in old paintings and in wax cylinder archives of arwhal songs, which have faded considerably in quality since the time of their recording.

—Rudgaard Vanderplast