Meeting Abstract

57.3  Jan. 6  Natural substratum topography and its relation to the prolific adhesive capacity of geckos RUSSELL, A. P.*; JOHNSON, M. K.; Univ. of Calgary; Univ. of Calgary arussell@ucalgary.ca

Many taxa of gekkonid lizards have subdigital pads bearing fields of adhesive setae that allow them to bond to and climb on a wide variety of surfaces in any orientation. Measurements of the maximal adhesive force that can be produced by individual setae and, in turn, by entire setal fields exceed the force necessary to support the body mass of these animals by as much as several thousand times. This enormous safety margin may be related to the types of surfaces that have been employed in studies where the adhesive capacity has been measured. Such studies have used primarily smooth or microscopically rough surfaces; however, the natural substrata of geckos may be very rough, undulant and unpredictable. On natural surfaces the adhesive system may be limited to very small patches of contact, and on any given footfall the actual adhesive contact made is likely to be very modest. Here we evaluate the microtopography of rock surfaces used by a southern African species of gecko of the genus Rhoptropus, and compare this to the form, configuration, compliance and functional morphology of its setal fields. Rhoptropus is diurnal, clawless and rock-dwelling, making it an appropriate subject for initial observations of the relationship between substrate microtopography and setal field morphology. Our results suggest that the design and adhesive capacity of gekkonid setal fields may well be adaptive features associated with undulant irregular surfaces, rather than smooth ones, as Rhoptropus exhibits setal field surface area very similar to that of other pad-bearing geckos.