Tongue flicking

Fig. 7.3 Chemoinvestigation among snakes and lizards by tongue-flicks.

Cooper W.E. Jr. (1994). Chemical discrimination by tongue-flicking in lizards a review. J Chem Ecol 20, 439-487. 

Gillingham J. and Clark D. (1981). Snake tongue-flicking transfer mechanisms to Jacobson s Organ. Can J Zool 59, 1651-157. 

Gove D. (1979). A comparative study of snake and lizard tongue-flicking, with an evolutionary hypothesis. Z Tierpsychol 51, 58-76. 

Graves B.M. and Halpem M. (1990). Roles of vomeronasal organ chemoreception in tongue flicking, exploratory and feeding behaviour of the lizard Chacides ocellatus. Anim Behav 39, 692-698. 

Greenberg N. (1993). Central and endocrine aspects of tongue-flicking and exploratory behavior in Anolis carolinensis. Brain Behav Evol 41, 210-218. 

Patterns of Tongue-Flicking by Garter Snakes (Thamnophis sirtalis) during Presentation of Chemicals under Varying Conditions... 

It is well known that the chemical senses play a critical role in the behavior of snakes (Halpern, 1987, 1992 Mason 1992 and Schwenk 1995). Tongue-flicking, a chemosensory behavior pattern unique to snakes and lizards (Gove 1979 Schwenk 1993), serves as the primary vehicle for transfer of chemical substances to the vomeronasal organ (Burghardt and Pruitt 1975 Graves and Halpern 1989 Halpern and Kubie 1980 Kahmann 1932 Wilde 1938). Snakes have well-developed vomeronasal systems and flick their tongues in response to odorants perceived in their environment. 

Snakes were trained to look for earthworm bits in a plastic 5-arm radial maze (similar to that used by Kubie and Halpern 1978,1979). At the beginning of every trial, the snake was placed in an open-ended cylinder placed in the center of the foraging apparatus. After 1 minute, the cylinder was lifted and the snake was allowed to explore the apparatus. During training, the goal box at the end of each arm of the maze was baited with earthworm bits to encourage the animal to enter each arm in search of food. Tongue-flick data was recorded before and after prey consumption. 

A square field (80 x 80 cm), with a milk-glass floor, marked off in 5 cm squares, opaque walls and a clear Plexiglas top was used. Snakes were placed in an open-ended cylinder and placed in the middle of the apparatus and the snake was allowed 1 minute to adapt. The cylinder was lifted and the snake was allowed to explore the apparatus for one minute during which tongue-flicks were videotaped. No prey or prey odor was ever placed in this apparatus. 

Autocorrelations were calculated on the time-series of tongue-flick duration scores during earthworm extract trailing. This was done for a series of tongue-flick-number shifts. So, for example, for a shift of 1 the autocorrelation paired each tongue-flick duration with the subsequent tongue flick duration. For a shift of two, the correlation paired each tongue flick duration with the second to follow. 

The present study has examined tongue usage in four experimental situations prey extract trailing, foraging, open-field exploration and during delivery of airborne odors. The same animals were tested in each experimental situation to facilitate comparisons of tongue-flick parameters in the different tasks. 

As previously reported (Halpern and Kubie 1983 Kubie and Halpern 1978) tongue-flick rates varied as a function of extract concentration (Fi.2,6.2 = 12.85, p = 0.009) with tongue-flick rates greatest when the snakes were following high concentration trails (IX) and lowest at the weakest concentration (1/8IX) and dry trails (Table 33.1). As expected from the above, tongue-flick initiation intervals, the inverse of tongue-flick rates, also varied as a function of earthworm extract con-... 

Table 33.1 Summary of Significant Results. Abbreviations AA = amyl acetate BTFI = between tongue-flick interval dH20 = distilled water EE = earthworm extract FW = fish water LEW = live earthworm MTFE = maximum tongue-flick extension > significantly greater than < significantly...

Traversing a maze in which no proximate odor cues are present, but in which snakes have previously received rewards was here defined as a foraging task. Such a task permits one to analyze tongue-flick patterns before and after prey consumption. 

Fig. 33.2 Autocorrelations calculated on the time-series of tongue-flick duration scores for snake S6 during trailing of IX earthworm extract...

Tongue-Flick Duration Before and After Tongue Touch... 

Six snakes were tested with airborne odors from earthworm wash, fish water, live earthworm, dE O, amyl acetate and lemon extract (Table 33.1). Tongue-flick rates increase during odorant delivery compared to before or after odorant delivery (Halpern et al. 1997 Halpern and Kubie 1983 Zuri and Halpern 2003). 

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