650 ANIMAL LIFE IN THE OCEAN. 



the surface waters of the North Atlantic Ocean, found the Sargasso Sea 

 to be surprisingly poor in animal life, but the transparency of its water 

 is truly remarkable, a white canvas disc being visible at a depth of 

 37 fathoms. 



From recent investigations, it is found that sponges, corals, crustaceae, 

 and molluscs are obtained from all depths, some soft-bodied creatures 

 even from a depth of 4 miles, where the pressure would be four tons on 

 the square inch. The eyes of deep-sea animals are very rudimentary, 

 but many are provided with sensitive delicate feelers. The " Plankton " 

 Expedition found that the number of organisms living in great depths is 

 very much less than in the upper strata, which are penetrated by the 

 light ; not only the quantity diminishes, but also the number of species. 

 A species of vesicular marine algcB was found in large quantities, at depths 

 from 500 to 1,100 fathoms; the Challenger scientists concluded that all 

 vegetable life ceased at 200 fathoms. 



The Challenger trawls brought up fish from depths of 2,900, 2,750, 

 2,650, and 2,500 fathoms ; the Albatross brought up similar fish from 

 2,949 fathoms; and the Talisman from 2,200 fathoms. Prof. Agassiz 

 remarks that " in fishes brought up from deep water, the swimming 

 bladder often protrudes from the mouth, the eyes are forced out of their 

 sockets, the scales have fallen off, and they present a most disreputable 

 appearance," all owing to the loss of pressure. 



In 1881, the French exploring vessel Travailleur, when off the coast of 

 Portugal, in depths of 800 to 1,000 fathoms, secured specimens of a large 

 fish of the shark family, which appear never to come to the surface. The 

 Portuguese fishermen also take such fish from a depth of 500 fathoms. 



In the deep sea, Dr. Carpenter remarks that animal life " is so in- 

 timately related to the temperature of the bottom, as obviously to be 

 determined by that condition in a much greater degree than by its depth. 

 This was very strongly impressed on Sir Wyville Thomson and myself in 

 our early investigations. For in the deep trough lying N.E. and S.W., 

 between Shetland and the Faeroe Islands, which, having been our cruising 

 ground in 1868, I have ventured to call the Lightning Channel, we found 

 at corresponding depths of between 500 and 600 fathoms, and sometimes 

 within a few miles of each other, two areas whose temperatures differed 

 by more than 13° Fahr. ; the bottom temperature of the ' warm area ' 

 being about 43°, while that of the ' cold area ' was somewhat below 30°. 

 The Fauna of these two areas showed the most marked diversities. I 

 was thus led, in my report for 1869, to express my entire concurrence in 

 the speculation thrown out some years previously by Professor Lov^n, 

 that ' there exists in the great Atlantic depressions, perhaps in all the 

 abysses of our globe, and continued from Pole to Pole, a fauna of the 

 same general character, thriving under severe conditions, and approaching 

 the surface where none but such exist, — in the coldest seas.'* 



• " Proceedings of the Koyal Society," 1869, page 475. The similarity of Antarctic 

 to Arctic forms of marine life had, indeed, been previously noticed by Sir James 

 Ross ; and had been attributed by him to the prevalence of a " similar temperature " 

 over the whole of the intervening sea-bed. This temperature, however, he erroneously 

 supposed to be 39-5° Fahr. 



