CHAPTER IX 



PELAGIC ANIMAL LIFE 



In the "Challenger" Summary, Sir John Murray writes as 

 follows: "The tow-net experiments carried out on board the 

 " Challenger " during several years in all parts of the world led me 

 to the conviction that these intermediate regions were inhabited, 

 although with a much less abundant fauna than the waters near 

 the bottom or those near the surface of the ocean. Thousands 

 of hauls of the tow-nets were taken in the surface and sub- 

 surface waters, and the contents were daily submitted to 

 microscopic examination ; the forms present in these waters 

 became quite familiar to the naturalists. When, however, the 

 tow-nets were sent down to deep water, and dragged in depths 

 as nearly as possible of 500, 1000, and 2000 fathoms, organisms 

 — such as the Tuscaroridse among the Radiolaria — were nearly 

 always observed in the gatherings in addition to the usual 

 surface organisms. Organisms from these intermediate layers 

 of water appear to have a much wider horizontal distribution 

 than the surface fauna or flora. These oft-repeated experiments 

 produced a strong belief that all the intermediate zones of 

 depth were inhabited. I am not aware that the Tuscaroridse 

 have ever been taken in the surface or sub-surface waters. It 

 is probable that the animals in the intermediate zones of depth 

 obtain their food by the capture of the dead organisms continu- 

 ally falling from surface to bottom. It is well known that the 

 deposits at the bottom are in most regions chiefly made up of 

 the dead shells and skeletons of surface organisms." ^ 



During the cruise of the Italian ship "Vettor Pisani," Captain 

 G. Palumbo constructed a closing-net with which Lieutenant 

 Gaetano Chierchia collected animals from accurately determined 

 depths. At the zoological station at Naples this work was 

 continued by Eugen von Petersen and Professor Carl Chun. 



^ Summary of Results Chall. Exp., p. 1455) 1^95' 



561 2 O 



