ABSTRACTThis paper considers the effects of claw morphology on the gripping efficiency of arboreal (Varanus varius) and burrowing (Varanus gouldiiandVaranus panoptes) lizards. To ensure a purely morphological comparison between the lizards, we circumvent the material effects of claws from different species, by modelling and testing claw replicates of the same material properties. We correlate climbing efficiency to critical morphological features including; claw height (hc), width (wc), length (lc), curvature () and tip angle (γ), which are expressed as ratios to normalise mechanically beneficial claw structures. We find that there is strong correlation between the static grip forceFsgand the claw aspectand the cross-sectional rigidity ratio, and milder correlation (i.e. higher scatter) with the profile rigidity ratio. These correlations are also true for the interlocking grip forceFintover different shaped and sized protuberances, though we note that certain protuberance size-shape couplings are of detriment to the repeatability ofFint. Of the three lizard species, the claws of the arboreal (V. varius) are found to be superior to those of the burrower lizards (V. gouldiiandV. panoptes) as a result of theV. variusclaws having a smaller aspect, a higher cross-sectional rigidity ratio and a small profile rigidity ratio, which are deemed noteworthy morphological parameters that influence a claw's ability to grip effectively.