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 rest length, and is about 7.5 inches (19.0 cm) long.
He needs a long, 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.
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
A: When I first read this question, I paused and tried to remember. Yes, it did seem like my hand went faster than my feet the last time I rode an escalator, but I wasn't sure.
So, one fine spring afternoon recently, I hopped in my red 4Runner, and headed north to the nearest big shopping mall: Cottonwood. I rode six escalators, all that Cottonwood had. Boarding each one, I clamped my elbow to my side (like I was holding a newspaper there) and reached for the handrail as I stepped on the moving stairs. My hand kept pace with the rest of my body. It did not tug me forward (moving faster) or push me backwards (moving slower). I concluded handrails do a good job of keeping even with the stairs.
The escalator drive shaft (which drives the stairs) also drives the handrail belts through a gear wheel and chain system. So the handrail system is closely, but not directly, coupled to the stair-drive system. Therefore, it's possible for a moving handrail not to keep exact pace with its moving stairs, according to Otis Elevator Company. However, all the escalators I rode that day had well-synchronized handrails.
I checked with the American Society of Mechanical Engineers about escalator handrail safety codes. "Though I cannot comment on a manufacturer's particular design," Geraldine Burdeshaw emailed, the code "does require the handrail to be substantially the same speed as the steps." I've included the pertinent safety code below.
Escalator information, Otis Elevator Company
Magic stairways, University of Houston
The Way Things Work: An Illustrated Encyclopedia of Technology, C. van Amerongen, 1967.
6.1.3.4.1 Type Required. Each balustrade shall be provided with a handrail moving in the same direction and at substantially the same speed as the steps. In the case of curved escalators, this shall be substantially the same angular velocity. The speed of the handrail shall not change when a retarding force of 450 N (100 lbf) is applied to the handrail opposite to the direction of travel.
(Answered April 9, 2007)