Features of a Chameleon's Tongue

The chameleon's slow-motion lifestyle and jerky movements belie his predatory prowess. Equipped like a sniper, with a long, gunlike tongue, the chameleon is able to capture prey from some distance away. While the chameleon typically preys on insects, he occasionally uses his remarkable tongue to capture small birds or lizards.

  1. Sequence of Events

    • When the chameleon spies a suitable prey item, he first attempts to get into a good position to extend his tongue. At this point, he often sways back and forth; this is thought to help him gauge the distance to the intended target. Then, while opening his mouth, the chameleon extends his tongue very slowly -- about halfway to the intended target. At the very last moment, the chameleon shoots his tongue out all the way, where it hopefully hits the insect. The tip of the tongue entraps the insect as the tongue withdraws, bringing the food into the chameleon̵7;s mouth. Once in the mouth, the food is chewed and swallowed.

    Length

    • Chameleon tongues are extremely long; some species have tongues that are one-and-a-half times as long as their bodies. The length of the tongue is important -- the chameleon isn't a nibble lizard and can̵7;t get close enough to catch prey with his mouth. With this long tongue, the chameleon can capture prey that may be on a completely different tree or bush than he is.

    Control

    • Equipped with stereo vision, the chameleon is able to guide his tongue right at the intended target. Experiments conducted on Jackson̵7;s Chameleons (Chamaeleo jacksonii) demonstrate their eyesight is extremely important to the aiming process. Researchers fitted a Jackson̵7;s chameleon with corrective lenses attached to his facial horns and then documented how the lenses distorted the chameleon̵7;s aim.

    Anatomy

    • The base of the tongue is attached to the hyoid bone, which is located near the back of the mouth. A long, cartilaginous projection called the hyoid horn is attached to the hyoid bone and provides structure to the tongue. A layer of connective tissue connects the cartilage to a layer of muscle. The connective tissue is pulled by muscles that enable the tongue to spring forward and catch prey. The tip of the chameleon̵7;s tongue is made of a mass of muscle tissue that conforms to the prey upon impact. This flexibility creates a suction-cuplike effect and further helps the chameleon capture its prey.

    Speed

    • The chameleon's tongue accelerates very quickly; up to 26 body lengths per second. According to Jurriaan H. de Groot of the Leiden University in the Netherlands, these speeds aren't possible by muscle power alone and require an energy storage mechanism. In a 2004 study, de Groot and colleague Johan L. van Leeuwen from Wageningen University in the Netherlands found that connective tissue between the hyoid cartilage and surrounding muscle functions as a catapult -- providing the energy storing mechanism necessary for the lizard's extraordinary abilities.