Ultrastructure and distribution of superficial neuromasts of blind cavefish, Phreatichthys andruzzii, juveniles

Transmission and scanning electron microscopy (TEM, SEM) were used to study the ultrastructure of superficial neuromasts in 15 six month old blind cavefish juveniles, Phreatichthys andruzzii (Cyprinidae). In 5 specimens examined with SEM, the number of superficial neuromasts over the fish body (480 to 538) was recorded. They were localized mainly on the head (362 to 410), including the dorsal surface, the mentomandibular region, and laterally from the mouth to the posterior edge of the operculum. Neuromasts were also present laterally on the trunk and near the caudal fin (116 to 140). A significantly higher number of neuromasts were present on the head compared to the trunk (t-test, P 0.05)