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When the weather cools, cold-blooded animals slow down, which should be good news for their potential prey. But the colorful chameleon, which can unfurl a tongue twice its body length in 0.07 second, does not lose much speed in unleashing its weapon.
To find out why, Christopher Anderson and Stephen Deban of the University of South Florida tested chameleons under different conditions, discovering that if temperatures dropped 10 degrees Celsius, tongue snaps slowed only by about 10 to 19 percent. The secret lies in the collagen tissue of the tongue, which uncoils based on momentum, not muscle activity. In contrast, under the same chilly conditions, the tongue movements of ectotherms, which rely fully on a muscle-based system, slowed by 42 percent.
The lizards, however, were not quite as quick to reel in their prey; the recoiling action, which depends on muscle contraction, fell by 42 to 63 percent. Considering that some chameleons inhabit locations where temperatures dip below freezing, the findings, described online March 8 in the Proceedings of the National Academy of Sciences USA, explain how the lizards can maintain such an extensive feeding niche.
