Figure 1. Surface fish and cavefish lateral lines are anatomically similar in early development.

Illustration (not to scale) of the canonical circuit of lateral line function depicting the neuromast (blue) comprised of mechanoreceptive hair cells that are innervated by ascending afferent neurons (green) that collect into the posterior lateral line ganglion. Putative cholinergic efferent neurons (red) descend from the hindbrain and project onto neuromast hair cells (A). 2-[4-(Dimethylamino)styryl]-1-ethylpyridinium iodide (DASPEI) staining of 6 dpf surface (n = 14, B) and cavefish (n = 17, C) show significantly different quantities of anterior lateral line neuromasts (p < 0.01, D) and similar quantities of posterior neuromasts (p = 0.77, E). Hair cells were labeled with a 30-min treatment of YO-PRO1 (green) and found to be of similar quantities between surface (n = 9) and cave (n = 11) populations (unpaired two-way t-test, p = 0.09, F). Box-and-whisker plot representing the number of hair cells per neuromast was indistinguishable across development (5–7 dpf; p = 0.06, G). Error bars are ± standard error (SE) and ** denotes a significant difference (p < 0.01) detected by an unpaired t-test.