LIGHT SENSITIVITY EXPERIMENTS AND MORPHOLOGY STUDIES OF THE BLIND PHREATIC FISH PHREATICHTHYS ANDRUZZII VINCIGUERRA FROM SOMALIA

SUMMARY Experiments with the anophthalmic phreatic fish Phreatichthys andruzzii Vinciguerra from Somalia revealed its sensibility to various monochromatic lights, particularly to blue light (480 nm). The anophthalmic condition is accompanied by a total lack of optic nerves and, in comparison to closely related visual species, a highly reduced encephalon particularly in the zone of the optic lobes. Though the site sensitive to luminous energy has not yet been identified, it can be hypothesized that this is located in the central nervous system.