As with other microchiropteran families, they use ultrasonic echolocation to sense the surrounding environment and their prey; the signals of some species are unusual in being audible to humans.

[3] Possession of the postorbital processes, the reduced, noncontacting premaxillaries, and rather simple shoulder and elbow joints, which is similar to pteropodids, makes them rather a primitive group.

The usual arrangement of the uropatagium is as to be fixed to the tail, but the sheathtail feature is joined by an elastic component which allows greater flexibility; they are able to use the hind legs for locomotion and to adjust the membrane's surface while in flight.

[4] As a common name indicates, many species also possess sac-shaped glands in their wings (propatagium), which are open to the air and may release pheromones to attract mates.

Species living away from the tropics may enter periods of torpor or extended hibernation during colder months.