The Colors of Fishes 



227 



colors, and especially metallic shades, take the place of oliva- 

 ceous gray or green. As we descend into deep water, especially 

 in the warm seas, red pigment takes the place of oHve. At a 

 moderate depth a large percentage of the fishes are of vari- 

 ous shades of red. Several of the large groupers of the 

 West Indies are represented by two color forms, a shore 

 form in which the prevailing shade is olive -green, and a 

 deeper-water form which is crimson. In several cases an inter- 



FiG. 167. — Garibaldi (scarlet in color), Hypaypopa rubicunda (Girard). La JoUa, 



,San Diego, California. 



mediate-color form also exists which is lemon-yellow. On 

 the coast of California is a band-shaped blenny {Apodichthys 

 flavidiis) which appears in three colors, according to its sur- 

 roundings, blood-red, grass-green, and olive-yellow. The red 

 coloration is also essentially protective, for the region inhab- 

 ited by such forms is the zone of the rose-red algtc. In the 

 arctic waters, and in lakes where rose-red alga; are not found, 

 the red-ground coloration is almost unknown, although red 

 may appear in markings or in nuptial colors. It is possible 

 that the red, both of fishes and algas, in deeper water is related 

 to the effect of water on the waves of light, but whether this 

 should make fishes red or violet has never been clearly under- 



