PELAGIC FAUNA 



77 



The catch from a bathy pelagic trawl at about 3,500 metres in the China Sea. Left, the medusa 

 AtoUa; top, the sea-cucumber Galatheathuria; right, another sea-cucumber, Enypniastes. 

 Also prawns and small fishes. 



underneath it. The common jellyfish (Aurelia) occurs near almost all the 

 coasts of the world in different varieties or closely related species. As a 

 rule, expeditions cannot afford the space to store such large and common 

 creatures, but we had an opportunity of comparing specimens found in 

 many different places. 



At deeper water levels nearly all fish and most cephalopods are black, 

 or at least very dark, and crustaceans are red. The deep-water species of 

 several zoological groups whose epipelagic species are colourless are also 

 red. In the dark all colours are as invisible as black. Some sunlight pene- 

 trates to the upper portion of the bathypelagic region, but not the red 

 rays, which are the first to be stopped. In this transitionary zone live a 

 number of fishes and cephalopods which are not black like the usual 

 deep-sea forms, but red like the prawns, red being invisible where red 

 rays are absent. Incidentally, it is likely that there is a connection between 

 red colours in animals and low temperatures; certain species of jellyfish 



