To catch prey from a distance, chameleons have a coordinated system of body parts that shoots out their tongues with high speed and power.
Introduction
The fast and furious flicks of chameleons’ tongues aren’t a novelty. They’re a key to their survival. When these reptiles sight prey, they launch their tongues like missiles and strike with stunning speed and force. Racing from 0 to 60 mph (96.5 kph) in a hundredth of a second, they can almost instantly reach a target twice their body length away.
This slow-motion video shows how chameleons can project their tongues farther than their body lengths. In real time, they launch their tongues with ballistic speed.
The Strategy
These awesome ballistic tongues are the result of a remarkable coordinated system of body parts that builds up and quickly releases energy. Here’s how it works.
At the core of a chameleon tongue is a slim, tubular bone wrapped in thin layers of elastic tissue. Enveloping all of this is a layer of muscle.
The elastic tissue is made of collagen, a common biological material that gets remarkable stretchiness from its springlike fibers. Half the fibers spiral clockwise and half anticlockwise. Together they form a diagonally crosshatched pattern that looks like the stretchy plastic mesh sleeves used to protect glass bottles.
When chameleons sight prey, they get ready, aim, and “load” their tongues by contracting their tongue muscles. The muscles squeeze inward around the collagen fibers, compressing them into tight coils. The fibers are now packed with stored energy, like a jack-in-the-box ready to pop.
The muscles and compressed collagen layers slide forward along the well-lubricated bone. At its tip, the bone thickness tapers down sharply, expanding the space for the collagen fibers. Suddenly uncompressed, the fibers spring forward, powered by their own momentum. Stored potential energy reverts to kinetic energy, amplifying the tongue’s speed and power. It shoots out at accelerations of 2,590 meters per second squared, or 264 G (faster than a fighter jet), and smashes its sticky tip into its prey within two-hundredths of a second.
To catch prey, chameleons have a highly coordinated system of bone, muscle, and connective tissue that shoots long distances out their tongues at high speed and power.
The tongue system also has another beneficial feature. Chameleons are cold-blooded, so their muscles slow down along with their metabolism in cold temperatures. But because the system relies on stored energy in the collagen layers rather than on muscle power, it continues to work well in temperatures ranging down to 59°F (15°C). After a cold night, just when they need food to refuel, their tongues are still fast enough on the draw—particularly to catch other cold-blooded critters that are still moving slowly.
Chameleons’ ballistic tongues are the result of a coordinated system of body parts: bone (entoglossal process = ep), collagen fibers (intralingual sheaths = is), and accelerator muscle (am).
The Potential
Chameleons’ highly refined and coordinated tongue system offers intriguing blueprints for scientists to explore ways to engineer projectile-motion mechanical systems and materials that store and release energy more efficiently, generate higher speed and power, and continue to work well in cold temperatures. Such innovations could be used in the fields of ballistics, missile engineering, robotic manipulator equipment, and prosthetic medical devices.
