Fig. 5.

Net cost of transport (NCT) for the terrestrial locomotion of limbed lizards and snakes adapted from (Secor et al. 1992). The values of NCT (±1 SE) for snakes are for a black racer (Walton et al. 1990) performing terrestrial lateral undulation (black circle) and concertina within a horizontal tunnel (white circle) and for sidewinding rattlesnake (triangle) on a treadmill (Secor et al. 1992). Diamonds are values for different species of lizards (John-Alder et al. 1986), for which a collective scaling equation (±95% CL) is shown. Note that the NCT of terrestrial lateral undulation of a snake is statistically indistinguishable from that of a lizard with similar mass, and NCT differs radically among different modes of snake locomotion.