. 2015 Feb 5;370(1661):20140027. doi: 10.1098/rstb.2014.0027

Table 2.

Scaling of pad area, as well as adhesion and friction forces with mass (m), body length (L) or pad area (A) for various groups of climbing animals. Note that the contact area data for hairy pads refer to ‘projected contact area’, i.e. they do not account for changes in hair-tip size or density. When scaling coefficients were not explicitly given (labelled with †), data were extracted using a web-tool (WebPlotDigitizer by Ankit Rohatgi, http://arohatgi.info/WebPlotDigitizer/), and scaling coefficients were estimated by performing reduced major axis regression on log-transformed values. Intraspecific data are labelled with a ‡. Where available, we give a range of the regression coefficients.

	animal	scaling	source
toe pad area	lizards (fibrillar pads)	m^0.59	[114]
		m^0.75–m^0.78	[115]
		m^0.60–m^0.80	[116]
		m^0.57–m^0.73‡	[117]
	tree frogs (smooth pads)	m^0.61–m^0.76‡	[118]
		m^0.65–m^0.90	[118]
		L^1.85	[119]
		L^1.76–L^2.29‡	[120]
		L^1.88	[121]
	insects (smooth pads)	m^0.27‡	[122]
		m^0.62‡	[109]
		m^0.58‡	[123]
		L^1.68–L^2.19‡	[124]
		m^0.54‡	[125]
		m^0.51–m^0.58‡	this study
	insects (fibrillar pads)	m^0.81†	[126]
	insects (fibrillar pads)	m^0.42–m^0.70†‡	[127]
adhesion	tree frogs (smooth pads)	A^1.19	[119]
		L^2.12–L^3.1‡	[120]
		L^2.19	[121]
	insects (smooth pads)	m^0.67–m^0.90	[128]
		m^0.5‡	[122]
		m^0.39‡	[122]
		m^0.38‡	[122]
		m^0.62	[122]
		m^0.57–m^0.87	[124]
		m^0.92–m^1.04‡	this study
friction	lizards	m^0.9–m^0.95	[115]
	lizards	m^0.45–m^0.65	[116]
	tree frogs	L^2.7	[119]
	insects (fibrillar pads)	m^0.74†m^0.84–m^1.56†‡	[126] [127]
	insects (smooth pads)	m^0.71‡	[123]