CHAPTER X 



THE COLOURS OF FISHES 



The Colours of the Lower Vertebrates — General Characteristics 

 of Vertebrate Coloration — Colours of Fishes, their Char- 

 acters and Distribution in Tropical, Abyssal, and Temper- 

 ate Forms — Coloration of Flat-fishes — The Pigments and 

 Structural Colours of Fishes. 



Of Vertebrates below fishes little need be said as to 

 colour or pigments. The Tunicates alone display 

 any marked colouring, and are often bright and varied 

 in tint. The pelagic forms are mostly transparent 

 and almost colourless, and, as we have seen, they are 

 often brilliantly phosphorescent. Those of sedentary 

 habit, on the other hand, often show a great range 

 of colour. Krukenberg describes the species of the 

 genera Didemnum and Botryllus, in the neighbour- 

 hood of Trieste, as exhibiting the following colours : 

 — blue, violet, yellow, yellowish-green, orange, brown, 

 and black, and observation on the shore confirms 

 this impression of prevalent brightness of tint. 



Krukenberg made a few observations on the pig- 

 ments which are of interest. The red and yellow 

 colours are apparently due as usual to lipochrome 



