Reversible, Light-Screening Pigment of Elasmobranch Eyes: Chemical Identity with Melanin

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Science  29 Oct 1965:
Vol. 150, Issue 3696, pp. 612-614
DOI: 10.1126/science.150.3696.612


There lies directly beneath the tapetum lucidum, in the eyes of many elasmobranch fishes, a layer of darkly pigmented choroid cells which, in bright light, extend individual strands that aggregate to form a dark, compound curtain which shields the reflecting tapetal cells. This process is reversed in dim light or in darkness; the tapetum is exposed and visual sensitivity presumably Increased. The black choroid pigment has been isolated, analyzed, and shown to possess the properties of melanin.