Species of the Caelus phylum are adapted primarily for flight. Possessing wings, either feathered or membranous, they can either fly or glide on updrafts to reach heights far beyond what their predators can reach. Gifted keen eyesight and hearing, they are expert trackers and hunters, able to snatch prey from several miles away at speeds almost imperceptible to the naked eye.

Numerous features shared with avian organisms, including a dense musculature and a hollow skeletal structure, aid them further in exceptional manoeuvrability and speed when in the air. Certain species lack usable wings, instead compensating with incredible leg strength, allowing them to easily keep pace with their airborne kin.