DWELLERS IN THE DEEP 



205 



that the lamp-like contrivances at the end of 

 the antcnnce in some fishes (notably the angler- 

 fishes) are to enable the fish to see or dazzle 

 prey; but it may be only a nervous manifesta- 

 tion indicative of fear, a defensive expedient to 

 frighten enemies, or possibly an allurement for 

 the opposite sex. The numerous hordes of 

 small creatures that float on the sea surface 

 and are known as "plankton" emit light, like 

 the fireflies in the grass ; but the reason for the 

 luminescence at either the sea surface or the 

 sea bottom is not easily determined. 



It seems that many of the polyps, medusce, 

 annelids, echinodcrms, molluscs and crusta- 

 ceans have luminous species; and that among 

 the bottom dwellers the lantern fishes are espe- 

 cially provided for in the matter of luminous 

 glands in the head or tail, or perhaps in regular 

 spots or photophores along the sides of the 

 body. Others of the species have lights near 

 the e3'es, and others again have an electric light, 

 as it were, suspended from a thin wire-like 

 bracket projecting from the top of the head. 

 All of these fishes are grotesque, somewhat dis- 

 torted specimens, being heavy of head and 

 small of body, with exaggerated eyes, large 

 mouths, and fang-like teeth. The bodies have 

 not the graceful proportions of the surface 



Plankton. 



Lantern 

 fishes uith 

 photo- 

 phores. 



Grotesque 

 quality of 

 deep sea 

 fishes. 



