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First published online January 8, 2007
Journal of Experimental Biology 210, 198-207 (2007)
Published by The Company of Biologists 2007
doi: 10.1242/jeb.02657
The desert ant odometer: a stride integrator that accounts for stride length and walking speed
1 Institute of Neurobiology, University of Ulm, Albert-Einstein-Allee 11,
D-89069 Ulm, Germany
2 Institute of Zoology, University of Zürich, Winterthurerstrasse 190,
CH-8057 Zürich, Switzerland
* Author for correspondence (e-mail: matthias.wittlinger{at}gmx.de)
Accepted 8 November 2006
Desert ants, Cataglyphis, use path integration as a major means of navigation. Path integration requires measurement of two parameters, namely, direction and distance of travel. Directional information is provided by a celestial compass, whereas distance measurement is accomplished by a stride integrator, or pedometer. Here we examine the recently demonstrated pedometer function in more detail.
By manipulating leg lengths in foraging desert ants we could also change their stride lengths. Ants with elongated legs ('stilts') or shortened legs ('stumps') take larger or shorter strides, respectively, and misgauge travel distance. Travel distance is overestimated by experimental animals walking on stilts, and underestimated by animals walking on stumps - strongly indicative of stride integrator function in distance measurement.
High-speed video analysis was used to examine the actual changes in stride length, stride frequency and walking speed caused by the manipulations of leg length. Unexpectedly, quantitative characteristics of walking behaviour remained almost unaffected by imposed changes in leg length, demonstrating remarkable robustness of leg coordination and walking performance.
These data further allowed normalisation of homing distances displayed by manipulated animals with regard to scaling and speed effects. The predicted changes in homing distance are in quantitative agreement with the experimental data, further supporting the pedometer hypothesis.
Key words: desert ant, Cataglyphis, navigation, stride integration, walking behaviour, odometer
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L. Blackburn PEDOMETER HELPS ANTS GET HOME J. Exp. Biol., January 15, 2007; 210(2): ii - ii. [Full Text] [PDF] |
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