In the Beginning was Information

ments with the black firefly (Photinus pyralis) it was found that the flyingmale emitted 0.06 second flashes at intervals of 5.7 seconds, and the femaleon the ground replied after exactly 2.1 seconds with the same rhythm.These flashing signals are obviously understood by the prospective mate.There also are insects that have lamps which emit different colours, like theBrazilian train worm (Phrixothrix). This beetle larva (Driliden) which liveson snails, normally carries two orange-red lights in front. At the approachof danger two sets of 11 greenish lanterns are switched on, one on eachside. This resembles a train, and the name “train worm” is quite apt.During a visit to Israel in 1985 we went to the underwater observatory inEilath and could watch the lantern fish (Photoblepharon palpebratussteinitzi) living in the Red sea. This fish does not produce its own light,but obtains it from symbiotic luminescent bacteria. These bacteria are sosmall that the light of a single one is invisible, but the light of an entirecolony can be observed. They congregate on an oval light organ situatedbelow the eyes of the fish and are fed and provided with oxygen through adensely branching network of capillary blood vessels. They continuouslygenerate light, but the fish can deliberately switch the light on and off. Itdoes this by pulling a black skin flap over the luminescent organ like aneyelid, and is thus able to transmit different flashing signals. These signalsattract the prey it requires for subsistence.Bacterial emission of light is fundamentally different from that of otherluminescent organisms. Other marine organisms only emit light whenthey are disturbed or stimulated (e. g. by the passage of a ship or of amackerel school, or the breaking of waves). But bacteria continuouslyemit light of a constant intensity.The bioluminescence of abyssal creatures, like glowing fishes, crabs,arrow worms, and jellyfishes, is quite impressive. Many kinds of fish havelamps along their sides, while others have several rows of lamps. Theluminous organs can be arranged in curves, in oscillatory patterns, or quiteirregularly. The five striped star constellation fish (Bathysidus pentagrammus)has five beautiful shining lines on both sides of its body, each ofwhich consists of a row of large pale yellow lights, surrounded by serratedbright purple “jewels”.Luminous shrimps (Sergestes prehensilis) have more than 150 light points,all of which can be quickly switched on and off. For one or two secondsyellow-green lights flash sequentially and quickly from head to tail justlike neon advertisements in cities. Many kinds of fish employ luminescentbacteria to generate light flashes, but others have highly specialisedorgans which produce their own luminous substances. Some fishes have239