Page:Popular Science Monthly Volume 92.djvu/374

 Deep-Sea Fish with Lanterns

Some fish carry their own power plants, searchlights, lenses and dimmers as if they were living automobiles

By Dr. E. Bade

Illustrations by the Author, supplied by Courtesy of American Museum of Natural History

���Some deep- sea fish are equipped with headlights which look very much like those on an automobile

��DEEP-SEA fish have been strangely influenced by that total darkness in which they live. Their eyes have lost their responsi\'eness to light and are therefore practically sightless. These blind fish are the in- habitants of those profound depths into which not even an infinitesimal ray of light can penetrate. In fact the fish must live in perpetual dark- ness. The eyes of some deep- sea fish are tiny; the eyes

of others are very large and round, as if they would catch some faint ray which may by some chance have penetrated these depths. But the most pecuUar thing about the deep-sea fish is that ap- proximately one fifth of them have developed some kind of a luminous organ, carried on this or that part of the body. Yes, even the whole body of some of the fish is illuminated, giving off to the surrounding water a faint iridescence as they glide along.

It's Deep Where They Live

Such lights are found not only on deep-sea fish, but on some varie- ties that live in well- lighted parts of the ocean as well.

��Two small varieties, commonly called "lantern fish," inhabit the Malay archi- pelago about the Banda Islands. A third variety has recently been discovered

near Jamaica. These three forms are the only ones upon whom the ac- tion of the organ of light can be o b- served under normal condi- ti o n s. The large, luminous organ, situated just below the eye, emits a greenish - white light, which is not steady but which flickers rhythmically. By pushing or pulling a skin over this organ the fish prevents all rays from escaping outward.

The light-organs of deep-sea fish are similar in structure. They were in all

���Other deep-sea fish have their bulbs, resembling portable electric lamps, attached to the tip of a long, movable stem

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