162 LIVING LIGHTS. 



about them ; so it is evident that predatory fishes possessing 

 lights have in their lure a decided advantage. 



Actual experiment has shown that the electric light can 

 be seen ninety-nine feet under water. The soft rays of 

 animal phosphorescence would not penetrate so far, but 

 would be powerful enough to illumine the water for some 

 distance about them. 



The deep-sea fishes which are not remarkable for their phos- 

 phorescence, or do not possess it at all, have feelers in many 

 instances, and grope about like blind men ; while others have 

 eyes that not only see, but are possible emitters of light 

 themselves. In the case of the predatory shark captured by 

 Bennett, we may assume that the light was an effective lure : 

 but the same will not apply to the brilliant scopelus and 

 other delicate little creatures almost completely defenceless ; 

 so that it will be seen that it is as difficult to lay down fixed 

 rules for the use of the light as to explain the cause of its 

 production. The phosphorescence of corals and their allies, 

 gorgonias, sea-anemones, etc., may serve to attract prey. 

 The minute crustaceans, so valuable to food fishes, are by 

 their unfortunate gift rendered visible to their enemies, and 

 the same may apply to many of the worms ; while in a certain 

 species of the genus Polynce, we have seen that the phos- 

 phorescent scales which it throws off may be used to delude 

 its enemies, just as when certain lizards cast off their tails, 

 and dart away, leaving them wriggling and squirming, to 

 attract the attention of their pursuers. Certain crustaceans 

 have luminous bands or spots which undoubtedly serve as 

 lanterns, while many have eyes that are modified into light- 

 emitting organs. The light produced inadvertently by 

 schools of mackerel, in their movements through water teem- 



