COLORATION 



211 



being either transparent and colourless, or with the head and 

 body covered with minute black dots, sometimes locally 

 aggregated to form larger masses, whose purpose is to break 

 up the outline of the moving body. In certain cases larval 

 forms may bear some resemblance to the little bubbles or 

 flecks of foam often to be seen floating on the surface of 

 the sea. 



Below the surface, fishes inhabiting the layers of water from 

 one hundred to five hundred metres are generally of a silvery 

 hue, although, curiously enough, a large number of species 



Fig. 82. COLORATION IN PELAGIC AND BOTTOM-LIVING SHARKS. 



A. Blue Shark {Carcharimis milberti),x-^^ ; b. Carpet Shark {Orectolohus har- 



baUis), X ^V- 



coloured with various shades of red also occur. It has been 

 suggested that the prevalence of this colour in fishes living at 

 moderate depths is in some way related to the effect of water 

 on the light waves, but this requires further investigation. 

 At greater depths still, five hundred to two thousand metres 

 below the surface, where there is little or no light, the prevaiHng 

 shades are brown, black or violet-black, generally quite dull, 

 but sometimes with silvery lustres or reflections from the scales. 

 There is also a complete absence of spots, bands, or other 

 distinctive markings such as distinguish the fishes which dwell 

 more or less close to the shore. 



