Directional asymmetry in snakes and its possible effect on injury rate

New evidence on directional asymmetry (DA) in lizards indicates a possible biological significance of this phenomenon. We examined bilateral morphological characters, supralabial and infralabial scutes, and eye diameter (spectacle) on the right and left sides, in seven snake species (from collections, Pavia and Hebrew University Jerusalem—R): Coronella austriaca (n = 12), Elaphe longissima (8), Hierophis viridiflavus (18), Natrix natrix (22), Natrix tessellata (6 from Europe; 72 from the Levant), Platyceps rhodorachis (41), and Vipera aspis (20). Significant DA occurred in three of the species, in different character-taxon-sex combinations: H. viridiflavus— infralabials in males; P. rhodorachis—eyes in females; V. aspis—infralabials in males and females. Significant positive correlation between DA of characters occurred in C. austriaca— between infralabials and eyes. Significant negative correlation occurred in P. rhodorachis—also between infralabials and eyes. We looked at the correlation of tail state (injured or intact) with DA in N. tessellata (from the Levant, of which our sample was the largest). A significant correlation occurred in the infralabials in males (intact: n = 44; injured: n = 5); the injured individuals were left-side dominant, while the intact individuals were symmetrical or right-side dominant. Although the biological significance of DA is not yet known, this study has two methodological conclusions: bilateral characters should not be examined consistently on one side only, and asymmetry should be tested separately in each sex. Breeding succes