10. Life in Great Depths 



Ihe important part played by marine biology in 

 stimulating interest in deep-sea research has already 

 been referred to in Chapter 2. Systematic investigations 

 by Forbes of the fauna in the Aegean Sea ( 1840-41 ) 

 led him to the conclusion that the number of species 

 and individuals decrease in inverse proportion to the 

 depth until a zero line is reached at a depth of 1,800 

 feet, where an azoic zone begins. This conclusion was 

 strongly contested during the following decades by 

 British and Scandinavian biologists who, along the 

 coasts of northwest Europe, found an abundant fauna 

 of marine organisms in depths considerably exceeding 

 that of Forbes' zero line. To continue and extend this 

 work into the still greater depths of the open oceans 

 was one of the main reasons for sending out the great 

 circumnavigating deep-sea expedition with H.M.S. 

 "Challenger" (1872-76) followed by expeditions from 

 the United States and countries in Europe. 



During the "Challenger" cruise living organisms 

 were raised from depths ten times greater than that of 

 Forbes' zero line. In the beginning of this century the 



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