LUMINOUS ORGANS 



743 



Fig. 895. — Battle at Sea. 



A deep-sea shrimp, Acanthephijra purpurea, secreting from its luminous gland 

 to blind its foe during a battle with the fish, Photostomias guernei. Note the luminous 

 organs behind the eye and on the vent ro- lateral surface of the latter (reproduced by 

 special permission from the Xational Geographic Society, after a painting by 

 E. J. Geske). 



luminesces brightly, presumably to attract attention, ^^hile in the vital 

 anterior part luminescence is inhibited, perhaps in order to aid in its escape 

 in the dark (Fig. 896). 



For other functions such as the luring of prey, there is little convincing evidence, 

 and, indeed, it would seem that in inany instances, for example in the luminescence 

 of fungi or bacteria or in many lower forms, the function can have little survival value. 

 It may be that in those cases the light is emitted incidentally as a by-product of 

 oxidative metabolism, a potentiality which has been seized upon for constructive 

 purposes by certain of the higher species. 



