Buccal expansion during hissing in the puff adder, Bitis arietans

Videoradiographic analyses were made of hissing in puff adders (Bitis arietans). During the hiss the larynx remains relatively stationary immediately adjacent to the internal nares. The exhalatory portion of the hiss is characterized by a distinct expansion of the caudal buccal cavity, including a depression of the hyoid and divergence of the cornua. This buccal expansion is hypothesized to be an epiphenomenon of intraoral pressure generated by the exhalatory airstream of the hiss.