PRESS RELEASE
Brussels, 21 June 2016
How chameleons capture their prey
Despite their nonchalant appearance, chameleons are formidable predators, capturing their prey
by whipping out their tongues with incredible precision. They can even capture preys weighing up
to 30% of their own weight. In collaboration with the Muséum national d’Histoire naturelle de
Paris, researchers from the Université de Mons (UMONS) and the Université libre de Bruxelles
(ULB) have studied this amazing sticky weapon. Their study is featured in the Nature Physics
journal.
Chameleons are fascinating creatures with amazing
characteristics. Their feet have opposable toes, giving
them a tongs-like appearance, to firmly grip branches
(Figure1). Their eyes move independently of each other
to provide 360 degree vision. Their skin changes colour
via the active tuning of a lattice of nanocrystals
contained in some cells. But their most outstanding
characteristic is probably their ballistic tongue, allowing Figure1: One of the chameleons
(Chamaeleo calyptratus) used for measuring
the capture of distant preys.
mucus viscosity and prey prehension kinetics
(courtesy of A. Maillard).
Despite their nonchalant appearance, chameleons are formidable predators, leaving little
chance to their prey. During a capture, their tongue whips out with an acceleration up to 1500
m/s² and extends to reach a length twice that of the chameleon's body. They are also able to
capture preys weighing up to 30% of their own weight. Sufficient adhesion between the prey
and the tongue is therefore necessary to catch such preys.
Under the leadership of Fabian Brau from the ULB Faculty of Science's Nonlinear Physical
Chemistry Unit, Pascal Damman from the UMONS Interfaces and Complex Fluids
Laboratory, Faculty of Science researchers from the UMONS, ULB, and Vincent Bels from the
Muséum national d’Histoire naturelle de Paris have just demonstrated that the mucus
secreted at the tip of a chameleon's tongue has a viscosity 400 times larger than the one of
human saliva. The tongue's deformability during projection, producing a large contact area
with the prey, together with this viscous liquid, form a particularly efficient adhesive weapon.
Published in the Nature Physics journal on 20 June, this interdisciplinary study, combining
experiments with a dynamical model of prey capture, allowed the researchers to shed light on
the basic mechanisms used by chameleons to capture their preys.
The authors used mechanical tools combined with tongue morphology measurements to
demonstrate that the viscous adhesion built up during a capture is large enough to catch preys
with a high mass compared to that of chameleons. Their theoretical model compares
favourably with experimental data on the maximum prey mass with respect to the chameleon
size.
These results provide a new methodology for studying prey prehension by other predators,
such as salamanders or toads, using the tongue to capture preys.
Fabian Brau, Déborah Lanterbecq, Leïla-Nastasia Zghikh, Vincent Bels, and Pascal Damman
Dynamics of prey prehension by chameleons through viscous adhesion
Nature Physics 2016, Advance Online Publication June 20, 2016, DOI:10.1038/nphys3795
Video: https://youtu.be/G9QZupjPUtg?list=PLtWiu4yEvwjaRsuQlKtWJZa4gzBIBZZkr
Scientific contacts:
Pascal Damman
UMONS, Interfaces and Complex Fluids Laboratory
Tel.: +32 65 37 38 19, Email: [email protected]
Fabian Brau
ULB Faculty of Science, Nonlinear Physical Chemistry Unit
Tel.: +32 2 650 59 12 – Email: [email protected]
Photos and videos are available for the press: please contact
Valéry Saintghislain, UMONS - [email protected], +32 (0)475 528 646
Or Nancy Dath, ULB – [email protected], + 32 (0)473 972 256