Figure 5. Normalized eye sizes for two species of salamander at different stages of development.

Two developmental stages (early vs. adult) were measured and scaled to head size for two species from the central Texas Eurycea clade exemplifying subterranean (E. rathbuni) and surface (E. sosorum) optics. ANOVA and a post-hoc Tukey’s test revealed that the ocular size of the adult E. sosorum was statistically significantly larger than the early stage E. sosorum and early and adult E. rathbuni. In contrast, there was no statistically significant difference between the ocular length of adult E. rathbuni and either embryonic salamander.