32 A TEXTBOOK OF OCEANOGRAPHY 



belonging to the family Macruridae and 8 Zoarcida3, as being 

 certainly captured on the abyssal plain. 



This is the total result of all attempts to capture bottom 

 fish beyond the 2,ooofathom line. This scarcity of fish is 

 associated with a scarcity of other forms of life. In the 

 Challenger reports large numbers of species of invertebrates 

 are know r n only from a single locality, and often from one 

 specimen only. The abyssal fish have a wide distribution, 

 both horizontal i.e., they are found at places wide apart 

 in the different oceans and vertical i.e., they occur on the 

 continental slopes as well as on the abyssal plain. 



FIG. 4. ABYSSAL FISH (MACRURUS). ) 



FIG. 4A. ABYSSAL FISH (LYCODES). 



Sir John Murray has summarised the results of the deep- 

 sea trawling and dredging of the Challenger expedition. At 

 25 stations where the depth exceeded 2,500 fathoms 600 indi- 

 vidual animals were captured; this gives 24 individuals per 

 haul. Many of these, however, are undoubtedly pelagic 

 certainly most of the Crustacea and some of the fish. 



Some of the other organisms were very small e.g., 

 hydrozoa and bryozoa. It is certain that animal life is very 

 poorly developed on the abyssal plain. 



The Norwegian fisheries' investigation steamer Michael 

 Sars has made three successful hauls at depths of over 2,500 



