Pelagic Environment 



161 



Figure 139. Example of bathyal fish — Caulolepis longidens Gill. This was obtained in a net haul from a depth of 830 

 meters at latitude 27°34', longitude 115°06'. Note that the teeth and mouth are typically large compared to the body 

 (Xl). 



torn, but twice when tow nets accidently 

 struck bottom they recovered specimens of 

 Nezumia liolepis, a fish belonging to the 

 family Macruridae which has been widely 

 collected elsewhere as bottom-living fishes. 

 It has a large head, huge eyes, tapering body, 

 and lengths as great as 20 cm. None of the 

 fishes is unique to the region; in general, 

 bathypelagic fishes are cosmopolitan, owing 

 to the world-wide uniformity of this environ- 

 ment. Good descriptions applicable to 

 deep-sea fishes of this region are given by 

 Murray and Hjort (1912) for collections 

 made in the North Atlantic Ocean and by 

 Clemens and Wilby (1946) for collections 

 off western Canada. 



Generalizations about the characteristics 

 and habits of deep-sea fishes are subject to 

 uncertainty, particularly because relatively 

 little more is known now than in the time 

 of Murray and Hjort (1912). However, in 

 a very general way we can state that the 



bright coloration of epipelagic fishes is ab- 

 sent at depth, replaced perhaps by patterns 

 of phosphorescent organs in fishes of the 

 mesopelagic zone. In general, the mesope- 

 lagic fishes are silvery, whereas the bathy- 

 pelagic ones are black. In place of the large 

 eyes of the mesopelagic fishes, the bathype- 

 lagic ones have small eyes and some are 

 blind, and the deep bottom-living fishes such 

 as those of the family Macruridae again have 

 large eyes, some exceptionally large. Other 

 characteristics of deep-sea fishes are their 

 large mouths and teeth, their usual ability 

 to swallow and digest animals larger than 

 themselves, tactile structures such as barbels 

 and long thread-like fin rays, and hook-and- 

 line and other lures for capturing prey. 

 How much the color, presence of photo- 

 phores, size of eyes, and development of 

 unusual structures depend on environment 

 rather than merely on the family represented 

 is not clear. 



