Among predators using an adhesive tongue to feed, chameleons are able to capture large prey by projecting the tongue at high acceleration. Once in contact with a prey, the tongue retracts with a comparable acceleration to bring it to the mouth. A strong adhesion between the tongue tip and the prey is therefore required during the retraction phase to ensure a successful capture. To investigate the mechanism responsible for this strong bond, the viscosity of the mucus produced at the chameleon’s tongue pad is measured, using the viscous drag exerted on rolling beads by a thin layer of mucus. Here we show that the viscosity of this secretion is about 400 times larger than that of human saliva. We incorporate this viscosity into a dynamical model for viscous adhesion, which describes the motion of the compliant tongue and the prey during the retraction phase. The variation of the maximum prey size with respect to the chameleon body length is derived, and compared with in vivo observations for various chameleon species. Our study shows that the size of the captured prey is not limited by viscous adhesion, owing to the high mucus viscosity and large contact area between the prey and the tongue.
This is a preview of subscription content, access via your institution
Subscribe to Journal
Get full journal access for 1 year
only $8.25 per issue
All prices are NET prices.
VAT will be added later in the checkout.
Tax calculation will be finalised during checkout.
Get time limited or full article access on ReadCube.
All prices are NET prices.
Schwenk, K. Feeding: Form, Function, and Evolution in Tetrapod Vertebrates (Academic, 2000).
Wainwright, P. C., Kraklau, D. M. & Bennett, A. F. Kinematics of tongue projection in Chamaeleo oustaleti. J. Exp. Biol. 159, 109–133 (1991).
Wainwright, P. C. & Bennett, A. F. The mechanism of tongue projection in chameleons I. Electromyographic tests of functional hypotheses. J. Exp. Biol. 168, 1–21 (1992).
Wainwright, P. C. & Bennett, A. F. The mechanism of tongue projection in chameleons, II. Role of shape change in a muscular hydrostat. J. Exp. Biol. 168, 23–40 (1992).
de Groot, J. H. & van Leeuwen, J. L. Evidence for an elastic projection mechanism in the chameleon tongue. Proc. R. Soc. Lond. B 271, 761–770 (2004).
Anderson, C. V. Off like a shot: scaling of ballistic tongue projection reveals extremely high performance in small chameleons. Sci. Rep. 6, 18625 (2016).
Herrel, A., Deban, S. M., Schaerlaeken, V., Timmermans, J.-P. & Adriaens, D. Are morphological specializations of the hyolingual system in chameleons and salamanders tuned to demands on performance? Physiol. Biochem. Zool. 82, 29–39 (2009).
Higham, T. E. & Anderson, C. V. in The Biology of Chameleons (eds Tolley, K. A. & Herrel, A.) 63–84 (Univ. California Press, 2013).
Herrel, A., Meyers, J. J., Aerts, P. & Nishikawa, K. C. The mechanics of prey prehension in chameleons. J. Exp. Biol. 203, 3255–3263 (2000).
Stefan, J. Versuche über die scheinbare Adhäsion. Sitz.ber. Akad. Wiss. Wien: Math. Nat.wiss. Kl. 69, 713–735 (1874).
Bikerman, J. J. The fundamentals of tackiness and adhesion. J. Colloid Sci. 2, 163–175 (1947).
Ewoldt, R. H., Clasen, C., Hosoi, A. E. & McKinley, G. H. Rheological fingerprinting of gastropod pedal mucus and bioinspired complex fluids for adhesive locomotion. Soft Matter 3, 634–643 (2007).
Denny, M. W. & Gosline, J. M. The physical properties of the pedal mucus of the terrestrial slug, Ariolimax columbanus. J. Exp. Biol. 88, 375–393 (1980).
Bico, J., Ashmore-Chakrabarty, J., McKinley, G. H. & Stone, H. A. Rolling stones: the motion of a sphere down an inclined plane coated with a thin liquid film. Phys. Fluids 21, 082103 (2009).
Briedis, D., Moutrie, M. F. & Balmer, R. T. A study of the shear viscosity of human whole saliva. Rheol. Acta 19, 365–374 (1980).
Harkness, L. Chameleons use accommodation cues to judge distance. Nature 267, 346–349 (1977).
Müller, U. K. & Kranenbarg, S. Power at the tip of the tongue. Science 304, 217–219 (2004).
Anderson, C. V. & Deban, S. M. Ballistic tongue projection in chameleons maintains high performance at low temperature. Proc. Natl Acad. Sci. USA 107, 5495–5499 (2010).
Herrel, A., Meyers, J. J., Aerts, P. & Nishikawa, K. C. Functional implications of supercontracting muscle in the chameleon tongue retractors. J. Exp. Biol. 204, 3621–3627 (2001).
Matthews, P. G. D. & Seymour, R. S. Haemoglobin as a buoyancy regulator and oxygen supply in the backswimmer (Notonectidae, Anisops). J. Exp. Biol. 211, 3790–3799 (2008).
Measey, G. J., Rebelo, A. D., Herrel, A., Vanhooydonck, B. & Tolley, K. A. Diet, morphology and performance in two chameleon morphs: do harder bites equate with harder prey? J. Zool. 285, 247–255 (2011).
Kraus, F., Medeiros, A., Preston, D., Jarnevich, C. E. & Rodda, G. H. Diet and conservation implications of an invasive chameleon, Chamaeleo jacksonii (Squamata: Chamaeleonidae) in Hawaii. Biol. Invasions 14, 579–593 (2012).
Deban, S. M., Wake, D. B. & Roth, R. Salamander with a ballistic tongue. Nature 389, 27–28 (1997).
Deban, S. M., O’Reilly, J. C., Dicke, U. & van Leeuwen, J. L. Extremely high-power tongue projection in plethodontid salamanders. J. Exp. Biol. 210, 655–667 (2006).
The lizard specimens were provided by C. Remy (Musée d’Histoire Naturelle de Tournai). The authors acknowledge C. Gay and D. Nonclercq for fruitful discussions. A. Maillard is acknowledged for the prey capture experiments. This work was partially supported by the MECAFOOD ARC research project from UMONS. F.B. acknowledges financial support from the Government of the Region of Wallonia (REMANOS Research Programme).
The authors declare no competing financial interests.
About this article
Cite this article
Brau, F., Lanterbecq, D., Zghikh, LN. et al. Dynamics of prey prehension by chameleons through viscous adhesion. Nature Phys 12, 931–935 (2016). https://doi.org/10.1038/nphys3795
This article is cited by
Limits of piriform silk adhesion—similar effects of substrate surface polarity on silk anchor performance in two spider species with disparate microhabitat use
The Science of Nature (2020)
Nature Physics (2018)