A Lashing Tongue

Q: How long is the veiled chameleon's tongue?
Stella, Hamilton, Canada

A: A veiled chameleon is a small animal — about 5 inches (12.7-cm) long, not counting his tail — with a tongue longer than he. The tongue can stretch to six times its resting length, and is about 7.5 inches (19.0 cm) long.

He needs a long and fast tongue because he is neither. The slow-moving creature never chases his prey but only edges towards it. He rocks a bit to judge the distance, focuses his independent swiveling eyes and unleashes his tongue to smite the insect from afar — up to one and a half body lengths away. The sticky tip gloms on.

The tongue whips out faster than our eyes can follow, speeding at 26 body lengths per second, according to two Dutch biologists: Jurriaan H. de Groot, at Leiden University and project leader Johan L. van Leeuwen, at Wageningen University. The tongue hits the prey in about 30 thousandths of a second — one tenth of an eye blink.

To move that fast, the chameleon stores energy in collagen, much as praying mantis and mantis shrimp do. He trips the apparatus, releasing his tongue like an arrow shot from a bow.

"When triggered, the concentric, overlapping sheaths of collagen telescope outward, allowing the adhesive tongue tip to extend rapidly toward the prey," explains National Geographic News.

Further Reading:

How chameleons change color, and why, WonderQuest
Shrimp spring into shattering action, WonderQuest
A hunting praying mantis, WonderQuest
Catapults give chameleon tongues super speed, National Geographic News.
Functional implications of super contracting muscles in the chameleon tongue retractors, the journal of experimental biology, 2001.
Veiled chameleons, Smithsonian National Zoological Park
International Wildlife encyclopedia, edited by Maurice Burton and Robert Burton

(Answered April 9, 2007)