National Geographic : 1978 Nov
source of light. Billions of the microorgan isms exist in each luminescent patch, called a photophore. By a chemical reaction simi lar to that in fireflies, the bacteria convert energy from food and oxygen in the fish's blood into a continuous supply of light. * Aquarium Glows With Living Light Despite its name, Photoblepharonhas no real eyelid. The photophore, however, has a fold of black skin on its underside that can be raised to cover the patch. Inside the photophore a layer of silvery crystals inten sifies the light emitted by the bacteria, as a telescope's mirror concentrates starlight. A film of black pigment lines the inner wall of the photophore, preventing the fish from being blinded by its own luminescence. After our dive the two Davids and I took our specimens back to the coastal city of Elat. Here David Fridman helps direct a public aquarium known as Coral World, next to Israel's highly regarded Heinz Stei nitz Marine Biology Laboratory. Dr. Moshe Shilo, director of the laboratory and an ex pert on marine bioluminescence, had wel comed our further study of Photoblepharon. As we released the captives into one of David Fridman's holding tanks, we were bathed once again in blue-green light, like a trio of witches stirring a luminescent brew. *See "Nature's Night Lights," NATIONAL GEO GRAPHIC, July 1971, and "Wing-borne Lamps of the Summer Night," July 1962, both by Dr. Paul A. Zahl.