KLEY, NJ; Stony Brook University: Form and function of the hyolingual apparatus in blindsnakes (Serpentes: Scolecophidia)

Tongue flicking is a chemosensory behavior known to occur widely among squamate reptiles (lizards and snakes). In general, tongue flicking is thought to be most highly developed in advanced snakes (Colubroidea), which exhibit rapid, multiple oscillation flicks. In contrast, most lizards perform slower, single oscillation flicks. However, the tongue flicking behavior of blindsnakes (Scolecophidia), which are phylogenetically intermediate between lizards and advanced snakes, has remained unknown. I used high-speed videomicroscopy to study tongue flicking in representatives of the three families of blindsnakes (Anomalepididae, Leptotyphlopidae and Typhlopidae). All species studied were found to exhibit rapid, multiple oscillation flicks. However, tongue flicking in the anomalepidid Liotyphlops was found to be unusual in two respects. First, the tongue is not protruded progressively further with each oscillation, as it is in leptotyphlopids, typhlopids, and other snakes. Rather, it is partially retracted between oscillations. Second, relative protrusion distances in Liotyphlops are much lower than those observed in leptotyphlopids and typhlopids. Studies of serial histological sections and whole-mount immunohistochemically stained specimens suggest that high-magnitude tongue protrusion in Leptotyphlopidae and Typhlopidae is facilitated by the morphology of the Mm. hyoglossi, which are extremely long due to the posterior position of the hyoid in these clades. The peculiar posterior placement of the hyoid in Leptotyphlopidae and Typhlopidae may have evolved to maintain the volume of the Mm. hyoglossi necessary for effective hydrostatic elongation of the tongue, as selective pressures acted to reduce the cross-sectional area of the head (and thus the tongue) during the early evolution of these highly miniaturized snakes.