ATSU Faculty Research

A combination of anatomical and experimental preparations was used to explore the function of the venom delivery system in rattlesnakes (Cro-talus). The distal end of the venom duct is compressed near the point where it empties into the venom chamber, a space surrounding the fang defined by the fang sheath. Within the venom chamber, the inner fang membrane lies obliquely over the base of the fang at least partially occluding the entrance orifice. When the fang is retracted the combination of the compressed venom duct and the spatial position of the inner fang membrane inhibit or block venom flow. As the fang is erected beyond approximately 60° (relative to the roof of the mouth) localized compression of the fang sheath decreases the size of the venom chamber, relieves the compressive force from the venom duct, and displaces the inner fang membrane away from the entrance orifice of the fang. Pressure recordings taken at different locations along the venom delivery system demonstrate that the venom gland produces suction during the relaxation of the extrinsic glandular musculature. These findings suggest that Crotalus's venom delivery system is more flexible and more regulated than previously assumed.

This is the common form of hearing among terrestrial vertebrates; though it has not been studied as extensively as the “independent” hearing of humans and some others mammals. In internally coupled ears, the contralateral middle ear cavities are connected through the skull (or pharynx) by patent air-filled ducts or tubes. With this construct, the displacement of one tympanic membrane creates an internal pressure which propagates, through the internal duct or tube, to drive the contralateral tympanum. I am particularly interested in the evolutionary diversity of internally coupled ears, as well as functional systems which evolved in different groups to modulate or tune the performance of these ears.