Small Chameleon’s Mighty TongueJanuary 7, 2016
Chameleons employ a power amplification mechanism to ballistically project their tongue as far as two body lengths from their mouth to capture prey. To do so, the tongue is rapidly accelerated off the hyoid with the tongue subsequently traveling to the prey on its momentum alone. Dr Christopher Anderson a postdoctoral research associate at Roberts Lab of Brown University wanted to find the upper limit of chameleon tongue projection performance. To do that, he gathered individuals of 20 species of widely varying sizes in his lab.
Anderson perched each chameleon one by one in front of a camera that shoots 3,000 frames a second. For each measurement, a cricket hung off a small dangling mesh to tempt the tongue to emerge. When it did, he could measure the distance the tongue went, the elapsed time, and the speed and the acceleration at any given time. In total, 279 feeding events from 55 different individuals were analysed. Anderson noticed that across all his measurements the smallest chameleons had the higher peak acceleration, more relative power, and greater distance of tongue extension relative to body size. Larger chameleons produced impressive motions too, but not compared to their smaller cousins. “All of the chameleons have the same catapult-like apparatus for launching the tongue, but proportional to their size, smaller chameleons have a bigger one than larger chameleons.” Dr Anderson said. The evolutionary reason why tiny chameleons are proportionately better equipped for feeding is presumed to be because, like all small animals, they need to consume more energy per body weight to survive. Their tongues have to burst out unusually fast and far to compete for all that needed nutrition. Because they’re smaller, they need to be better at the same game than their bigger cousins. According to Dr. Anderson examining movements in smaller animals may expose movements harbouring cryptic power amplification mechanisms and illustrate how varying metabolic demands may help drive morphological evolution.”
Although shrinking the human body might not immediately influence the size of The Incredible Shrinking Man’s tongue, the same metabolic rules apply for humans too. What would Shrinking Man get better at?