CH. Ill] LIFE IX THE SEA 61 



an exaggerated statement to make when one says that there is 

 not a square foot of the North Sea which has not been sounded by 

 the fishermen, and certainly there is not any part of that sea 

 where it is possible to trawl that has not been swept by the net. 

 When one compares our knowledge of the shallow seas with that 

 of the deep ocean bed, derived fi:-om the very few hauls of the trawl 

 or dredge, which have been made there it is not so certain that 

 our experience justifies us in assuming that animal life there 

 is enormously less abundant than in the inshore seas. Certainly 

 the deep sea is not even relatively sterile. 



Before the time of the great oceanographical voyages naturalists 

 thought of the exceptional conditions prevailing at the bottom of 

 the deep oceans : the utter darkness, compared with which even 

 the obscurity of a moonless night is relatively light ; the enormous 

 pressure which organisms living there have to undergo (in 3000 

 fathoms approximately three tons to the square inch); the uniformly 

 low temperature which they correctly supposed to obtain in the 

 depths ; the supposed stagnation or imperfect aeration of the water 

 at the bottom — all these conditions pointed to the absence of life, 

 and such a 'priori speculations could only lead to one conclusion, 

 that the great oceanic abysses were regions of desolation. 



When isolated observations made before the voyage of the 

 Challenger rendered it probable that the deepest recesses of the 

 ocean were the abode of life, expectations of strange results when 

 these were adequately explored w^ere entertained. It was probable 

 that the geological antiquity of the ocean beds was very great, 

 and since conditions must be very uniform there it was imagined 

 that deep-sea trawling would reveal " living fossils," animals akin 

 to those which flourished during past geological epochs. Now 

 while many characteristic deep-sea animals present archaic 

 features — the stalked crinoids for instance — it is nevertheless the 

 case that these expectations have been disappointed. The deep- 

 sea fauna is peculiar, but all the same it exhibits a general re- 

 semblance to that of shallow water. There is no deep-sea flora 

 for, since light is entirely absent except for that which is afforded 

 by the phosphorescence of most of the animals residing there, 

 plants cannot exist. But with this exception all the groups of 

 living things found on shallow water are represented. Echinoderms 



