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First published online February 27, 2009
Journal of Experimental Biology 212, ii (2009)
Copyright © 2009 The Company of Biologists Limited
doi: 10.1242/jeb.030379
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LIZARDS ADJUST MOVEMENTS AS THEY BITE
kathryn{at}biologists.com
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Every creature has its own dining style. Some animals locate fruit lunches before sitting down to munch, while others sneak up and grab an unsuspecting snack. And then there are different ways to snag a meal. Some lizards fire out sticky ballistic tongues, while others snap up treats with their jaws. But getting a meal isn't just about what you do with your mouth. While some lizards seem to feed perfectly well by simply sticking their tongues out, most animals have to move too. Which made Stéphane Montuelle and Vincent Bels from the Muséum National d'Histoire Naturelle in France wonder how closely correlated the two systems are. Having previously found that Anolis lizards always use the same jump pattern when capturing prey with their tongues, Montuelle and Bels decided to test out the table manners of other lizards to find out whether other species can adjust their body movements in response to different feeding actions (p. 768).
Knowing that Gerrhosaurus major lizards seem equally happy using their tongue and jaws to catch prey, the duo contacted Anthony Herrel in Antwerp to see if they could test out his Gerrhosaurus lizards' eating habits. Travelling down to Paris with his lizards on the train, Herrel offered the lizards meals ranging from stationary morsels of banana to super-fast grasshoppers while Paul-Antoine Libourel and the rest of the team filmed the animals with a high-speed 3D camera rig to find out how the reptiles adapted their feeding styles to different diets. Herrel remembers that the lizards were fantastically cooperative and they had collected all of the film data within a week, but analysing the data with the help of engineer Lionel Reveret was much more laborious for Montuelle.
So how did the lizards grab lunch? According to Herrel the lizards had two clear strategies depending on the prey type. They opted to land lumps of banana and slow moving meal worms with their tongues, while snapping up larger and faster mice and grasshoppers with their jaws. Herrel admits that he was surprised that the lizard's behaviour was so clear cut. He explains that feeding strategies in other species don't seem as hard wired as they are in Gerrhosaurus. For example, each individual Anolis lizard selects its own strategies, but always uses the same strategy for that particular morsel.
The team was also surprised that in contrast with the Anolis lizards, which never vary their jump pattern when catching food with their tongues, the Gerrhosaurus majors always adjust their movements to some extent. The amount that the animals reared up seemed to depend on their victim's mobility, with the lizards straightening their elbows most to capture the fastest grasshoppers. And when the team analysed the extent to which the lizards threw their jaws wide, they found the lizards could open their mouths faster the higher they reared up, giving them the element of surprise over their victims and increasing their chances of success.
Having found that the lizard's feeding actions and body movements were tightly coupled, Bels and his colleagues are curious to know how the reptiles synchronize their mouths with their bodies to snatch a snack.
References
Montuelle, S. J., Herrel, A., Libourel, P.-A., Reveret, L. and
Bels, V. L. (2009). Locomotor–feeding coupling during
prey capture in a lizard (Gerrhosaurus major): effects of prehension
mode. J. Exp. Biol. 212,768
-777.
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