THE ABYSMAL ZONE LIFE IN DEEP WATER 



445 



colour, red, and even white, while others are spotted or striped 

 in a simple manner. The hard investment of the body is 

 comparatively thin and free from lime. As among Fishes, we 

 find that the eyes are either greatly developed, or else more or 

 less degenerate. We may take as an example of the former 

 condition a kind of Prawn 

 ( Glyphocrangon priononota, fig. 

 1298) inhabiting the Indian 

 Ocean at depths of 865-1022 

 fathoms. The figure illustrates 

 two other interesting features. 

 One branch of the first feelers 

 (the thicker of the two fila- 

 ments seen projecting in front) 

 is of large size, and as this is 

 the region which bears the 

 olfactory organs the possession 

 of a keen sense of smell may 

 be inferred. There is, further, 

 a sharp defensive spine at the end of the tail, which can be turned 

 up and held in that position by a sort of ''locking joint", acting 

 as a bayonet to repel enemies at close quarters. It also appears 

 that in some deep-sea crustaceans the fluid excreted from the 

 renal organs gives out a phosphorescent light. In another kind 



Fig. 1299. Large Eyes of a Deep-Sea Prawn (Para- 

 pandahis spinipes], enlarged, a, Accessory eye (?) or 

 luminous organ (?). 



Fig. 1300. A Blind Deep-Sea Shrimp (Prionocrangon ommatosteres] 



of Prawn (Parapandalus spinipes, fig. 1299) there is what looks 

 like a small accessory eye near the big one. If, however, this 

 is really a luminous organ, as some think, the prawn provides 

 its own eyes with light. 



To illustrate blind crustaceans we may take one of the 

 Shrimps (Prionocrangon ommatosteres, fig. 1300), which is 

 absolutely destitute of eyes. 



