abyssopelagic community might be called oligomictic. The extreme 

 sparsity of plankton, apparently, makes even passive predation energetically 

 inexpedient, and carnivorous species almost disappear. The plankton at 

 these depths consist primarily of small detritophages or omnivores. The 

 species poverty of the abyssopelagic zone results also from the fact that, 

 given the great sparsity of the population, the dispersion of the dis- 

 tribution of individual species increases so greatly that the sexes do 

 not encounter each other sufficiently frequently to breed. The population 

 of the greatest depths, having the lowest total number, can exist only 

 with comparatively homogeneous species composition. 



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