234 OF DEEP-SEA FISHES IN GENERAL 



That the true deep-sea fishes, namely those that 

 live permanently in the still seclusion of the abysses, 

 consume less oxygen than their shallow-water relatives 

 is inferred from the fact that their gill-plates are so 

 much smaller. In some cases, indeed, as in many of 

 the deep-sea Anglers, the gill-plates are reduced, not 

 only in size, but also in number, being present on 

 only two of the gill-arches on either side. 



Owing to the fact that, as a consequence of the 

 eternal darkness, there is no vegetation in the great 

 depths of the sea, the abyssal fishes are all carnivorous. 

 It is perfectly true, of course, that most shore fishes 

 are carnivorous also, but nowhere do we encounter 

 such an enormous gape of mouth, such a formidable 

 array of teeth, and such insatiably-distensible stomachs 

 as we do among certain fishes of the deep sea ; but 

 this is a matter to be referred to later on. 



Before the year 1881, when the Investigator began 

 her explorations, nothing at all was known of the 

 fishes that dwell in the depths of the northern reaches 

 of the Indian Ocean, for the Challenger seems to 

 have left this part of the sea to local naturalists. 

 Since then, however, we have learnt that these depths 

 are thickly populated with fishes, the majority of which 

 resemble the deep-sea fishes found in other parts of 

 the world, and are therefore quite unlike the familiar 

 shore fishes of the Oriental region. Thus among the 



