63. What is bioluminescence? 



Bioluminescence is light produced by living organisms, both animals 

 and plants. In contrast to incandescent light, high temperatures are not 

 necessary; oxygen, however, appears to be essential to the light- 

 producing process. 



Thousands of species of marine animals produce bioluminescence; 

 most of them are animals of the lower orders. In addition to single- 

 celled animals, various jellyfish and related animals produce displays. 

 Among vertebrates, luminescence is found only in certain fishes and 

 sharks. 



Displays are seen most commonly in warm surface waters. Although 

 most of the organisms are small, there are such immense numbers 

 present that brilliant displays occur when the waters are disturbed by 

 the passage of a ship at night. 



Luminescent bacteria are present in sea water, but not in fresh water, 

 and can cause decaying fish to glow in the dark. 



At ocean depths where light does not penetrate, there are strange- 

 looking luminescent fishes. Beebe estimated that 96 percent of all the 

 creatures brought up by nets were luminescent. There is controversy 

 among biologists concerning the purpose of lights on marine animals. 

 Some creatures have well-developed eyes but no light to enable them to 

 see in the dark; others have brilliant light organs but are too blind to 

 see. The property of luminescence is perhaps used as a defense against 

 predators or as a means of hunting food or finding members of the 

 opposite sex in the dark. 



Cromie, William J. 



Exploring the Secrets of the Sea, Prentice-Hall, 1962. 

 Klein, H. Arthur 



Bioluminescence, J. B. Lippincott Company, 1965. 

 Yasso, Warren E. 



Oceanography, A Study of Inner Space, Holt, Rinehart and 



Winston, 1965. 



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