Gecko and lizard adhesion: A whole-organism perspective
Photo by Margarita Ramos
How do animals adhere to surfaces? We are investigating this question by taking a whole-organism perspective. We examine how a variety of different factors, such as temperature, substrate type, morphology, and habitat use all affect adhesion in lizards with toepads, such as geckos. As one example, we are investigating the role of loading and adhsesion as limiting factors for locomotion in pad-bearing lizards. A key question in evolutionary physiology concerns which factors affect how fast or how far animals can move. This is a particularly important issue for climbing animals, which often must move directly against gravity, and hence must exert considerable power to move. Nevertheless, many climbing animals, such as geckos (shown above) can climb uphill with remarkable speed and agility. An ongoing line of inquiry in our laboratory is to understand which factors limit the ability of such arboreal lizards to effectively climb. Recent work (Irschick et al. 2003) examined how two geckos species varying in size (G. gecko and H. garnoti, above) differ in the amount of mechanical power output when running uphill at maximum speeds, and with large loads present (up to 200% of body weight). Most surprising was that these geckos were quite effective at running uphill with very large loads, although the small gecko ran more effectively with the large loads. Another interesting result was that total power output did not limit maximum speed in both species. This result stands in contrast to other recent work on terrestrial locomotion which shows that power indeed limits maximum speed during maximum speed horizontal running.
Relevant publications:
Irschick DJ, Austin CC, Petren K, Fisher RN, Losos JB, Ellers O. 1996. A comparative analysis of clinging ability among pad-bearing lizards. Biological Journal of the Linnean Society 59:21-35.
Irschick DJ, VanHooydonck B, Herrel A, and Androsceu A. 2003. Effects of loading and size on maximum power output and kinematics in geckos. Journal of Experimental Biology. 206:3923-3934.
Elstrott J, Irschick DJ. 2004. Evolutionary correlations among morphology, habitat use and clinging performance in Caribbean Anolis lizards. Biological Journal of the Linnean Society. 83:389-398.
Vanhooydonck B, Andronescu A, Herrel, A, and
Irschick DJ. 2005. Effects of substrate structure on speed and
acceleration capacity in climbing geckos. Biological
Journal of the Linnean Society. 85:385-393.
Bloch N*, Irschick DJ. 2005. Toe-clipping dramatically reduces clinging performance in a pad-bearing lizard (Anolis carolinensis). Journal of Herpetology. 39:288-293.
Bergmann P, Irschick DJ. 2005. Effects of temperature on maximum clinging ability in a diurnal gecko: Evidence for a passive clinging mechanism? Journal of Experimental Zoology. 303A:785-791.