COLORATION 



215 



the Rays (Raia), Flat-fishes (Heterosomata) , Anglers {Lophiidae) 

 and other fishes, have the upper surface coloured in harmony 

 with the ground on which they are lying. Most of the Frog- 

 fishes {Antennariidae) are shore-dwelling forms, but the species 

 of the genus Pterophryne live in the open sea, drifting about with 

 the currents in masses of sargassum. The particular species of 

 the Sargasso weed of the Atlantic is of a pale yellow colour, 

 with small white spots and irregular brown bands, giving an 

 almost perfect concealment in its natural habitat among the 

 weed (Fig. 85). 



Fig. 85. 

 Frog-fish {Pterophryne tumida) in Sargasso weed, X J. 



In some fishes the protective resemblance is carried still 

 further by actual mimicry, both in form and colour, of a 

 particular inanimate object. For example, the Pipe-fishes 

 {Syngnathidae) , not only in their shape and colour, but also 

 in their slowly swaying movements, bear a marked resemblance 

 to the fronds of seaweed among which they live. The Florida 

 Pipe-fish when among tufts of eel-grass is said to be dark green 

 in colour, but when placed in an aquarium among pale weeds 

 it becomes light green. Another American form is normally 

 of a muddy brown hue, but examples collected from a tide- 

 pool filled with red seaweeds were brick-red in colour. The 

 grotesque Sea Dragon {Phyllopteryx) of Australian shores has 



