Fig. 2: Correlations between linear measurements of the tooth. a. Tooth length and mean angle, b. tooth length and maximal angle, c. mean angle and maximal angle. Each dot represents one species and is colored and shaped according to the main mechanical challenge encountered during feeding (legend above the graph).
The main mechanical feeding challenge is significantly related to the three measurements (LC: F=4.03, P=0.03, mean angle: F=4.49, P=0.02, max angle: F=5.06, P=0.01). Pairwise comparisons show that snakes that must hold their prey have longer teeth than snakes feeding on hard prey and snakes feeding on slippery prey which both have a larger mean and max. angle of curvature than snakes feeding on hard and long prey (Fig. 3, Table 1).
Prey hardness is also related to tooth length (F=5.93, P=0.01), mean curvature (F=6.38, P=0.01), and the maximal angle of curvature (F=4.93, P=0.03). Snakes feeding on hard prey have shorter teeth than snakes preying upon soft prey. Snakes feeding on prey of intermediate hardness have more curved teeth than durophagous species (Fig. 3, Table 1).
The medium in which species feed is also significantly related to the mean (F=9.97, P=0.001) and maxima of curvature (F=5.14, P=0.03) but not to tooth length (F=2.61, P=0.15). Snakes that forage under water have more curved teeth than snakes feeding on the ground. The average curvature of snakes feeding in trees is almost significantly higher than terrestrial species (t=-2.34, P=0.052, Fig. 3).
Finally, prey shape is not significantly related to the length and curvature (all P>0.3).