ANIMAL LIFE OF THE DEEP SEA BOTTOM 167 



the Challenger and has been a source of wonder owing to the enormous 

 flat, yellow organs on the top of its head. These organs have a cellular 

 structure rather Hke honeycombs, and luminescent powers are ascribed 

 to them. This is very probably correct, in which case they presumably 

 serve to lure other weak-sighted deep-sea animals, so that the fish need 

 only lie still on the bottom and snap its rather large mouth when it per- 

 ceives movement in the water near the organ. 



It will be obvious that with a trawl like the one described we had our 

 hands full in the laboratory, preserving and logging — and getting ready 

 for the next trawl. Lest it be thought that the trawl of March lo was an 

 altogether exceptional one, let me say that the following day we had one 

 with 20 bottom-dwelling fishes, spread over eight species, from a depth of 

 4,820 metres, and a further one on March 13, at 3,970 metres, when we 

 took nine bottom fishes belonging to four species, before moving on to 

 lower depths en route for Mombasa. The invertebrates were cQuallv well 

 represented; for example, there were, in the respective trawls, 83 and 27 

 hermit crabs and about 300 and 500 brittle-stars. 



Considering that, according to a survey made in 1952, the total catches 

 of bottom-dwelling fishes from depths greater than 4,000 metres known 

 to have been got by all previous expeditions were 1 1 8 individuals belong- 

 ing to 36 species, our total haul of 133 is obviously a great advance. As 

 a matter of fact, fishes are not the best illustration of the extent of the 

 Galatheas collections, because, as we shall see later, they do not occur 

 at the greatest depths. But there is good reason to believe that the volume 

 of our catches of bottom-dwelling invertebrates will show a similar ratio 

 to those of all previous deep-sea expeditions. However, it would be a 



Semi-transparent blind brotulid (Aphyonus) from the Indian Ocean, 4,360 metres. Length, 

 eisht centimetres. 



