Chameleons may look like mild-mannered, color-changing lizards, but don’t tell that to a cricket or a fly who happens to get too close. A new study highlights that a chameleon tongue can accelerate from 0 to 60 in a hundredth of a second and catch an insect up to 2.5 body lengths away.
In a new study published Monday in Nature’s Scientific Reports, Brown University postdoc researcher Christopher Anderson explains how chameleons can do the amazing things they do with their ballistic tongues:
“Stretching elastic tissues and using their recoil to power movement allows organisms to release energy more rapidly than by muscle contraction directly, thus amplifying power output. Chameleons employ such a mechanism to ballistically project their tongue up to two body lengths, achieving power outputs nearly three times greater than those possible via muscle contraction. [In thus study,] feedings with peak accelerations of 2,590 m s-2, or 264?g, and peak power output values of 14,040 W kg-1 are reported. These values represent the highest accelerations and power outputs reported for any amniote movement, highlighting the previously underestimated performance capability of the family. These findings show that examining movements in smaller animals may expose movements harboring cryptic power amplification mechanisms and illustrate how varying metabolic demands may help drive morphological evolution.”
More on chameleon tongue study
In undertaking the new research, Anderson used a high-speed video recording system to capture the tongue-shooting movements of 55 individual chameleons of 20 different species, from a tiny 1.6 inches to a relatively large 7.8 inches long. The study determined that these chameleons could project their tongues on average 1.5 times their body length, and a few species could extend their tongues an amazing 2.5 times their body lengths.
The study analysis included 279 individual chameleon feeding events, each recorded at around 3,000 frames per second,
In his write up, Anderson noted that Rhampholeon spinosus, the smallest of the chameleon species he looked at, had a tongue that extended a stunning 2.5 times the length of its body. Moreover, the tongue of the Rhampholeon spinosus traveled at a speedy 8,500 feet per second. That’s 264 times the force of gravity at sea level, or “gs” in Air Force and NASA parlance.
Think of it this way — if the chameleon’s tongue was a car, a very fast car, it could go from 0 to 60 in a hundredth of a second, but since the tongue only has to travel a foot or less, it only accelerates for a couple of milliseconds before it connects with its insect target.
Keep in mind that larger lizards can evolutionarily “afford” to be less efficient in terms of their body mechanics. Furcifer oustaleti, a close to two-foot-long on average chameleon species that was the largest among the 20 species Anderson studied, produced peak acceleration rates of around 18% less than the much smaller Rhampholeon spinosus.
Turns out smaller is stronger when it comes to chameleon tongues
A closer look at the study data made it clear that the smaller the chameleon, the farther its tongue projected from its body, the faster it accelerated and the more powerful the tongue was.
“Power output — we’re talking 14,000 watts per kilogram,” Anderson pointed out, referring to the rate energy is released by the chameleon tongue. For comparison purposes, the peak power ever seen in vertebrate muscles is the beating quail wings taking off vertically at 1,100 watts per kilogram, less than a tenth of the power output of the Rhampholeon spinosus tongue.
In his comments, Anderson did note that the tongues of salamanders (the amphibian “lizard”) have been recorded as accelerating slightly faster than the chameleon tongues he studied, but the Rhampholeon spinosus top all other reptiles, birds and mammals in tongue power.
Anderson went on to explain that “as body size increases, acceleration capacity decreases, So, small organisms, based on physics alone, are expected to have high accelerations.”
He continued to explain that smaller is stronger also makes sense from an evolutionary perspective. Given that smaller chameleons need relatively more nutrition per ounce of body weight than their larger relatives to keep themselves fully active, having ballistic tongues makes evolutionary sense as it allows the smaller lizards to catch more prey.