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The desert ant odometer: a stride integrator that accounts for stride length and walking speed


Wittlinger, M; Wehner, R; Wolf, H (2007). The desert ant odometer: a stride integrator that accounts for stride length and walking speed. Journal of Experimental Biology, 210(Pt. 2):198-207.

Abstract

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.

Abstract

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.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Institute of Zoology (former)
Dewey Decimal Classification:570 Life sciences; biology
590 Animals (Zoology)
Language:English
Date:January 2007
Deposited On:11 Feb 2008 12:14
Last Modified:21 Nov 2017 13:20
Publisher:Company of Biologists
ISSN:0022-0949
Additional Information:Free full text article
Publisher DOI:https://doi.org/10.1242/jeb.02657
PubMed ID:17210957

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