82 



PELAGIC FAUNA 



observed the same thing in another prawn, 

 a Hoplophorus, and in an aquarium test 

 we found this exceptionally animated when 

 the temperature was between 15 and 20 

 degrees c.; it probably lived at a depth of 

 300 — 400 metres. Notable among the nu- 

 merous deep-sea prawns which we took is 

 HymenopencBus, the largest of the prawns, 

 with a length of 30 centimetres from the 

 tip of the frontal horn to the tip of the tail. 

 It has unusually large abdominal legs with 

 broad fringes of bristles, and must be a 

 powerful swimmer. We found an excep- 

 tionally large and handsome species of the 

 genus Notostomus, which has a high, sharp 

 crest on the carapace. It was taken between 

 Mombasa and the Seychelles at a depth 

 of between 3,400 and 3,800 metres, and 

 about 1,500 metres from the bottom. It 

 proved to be a new species ( Fig. 81). 



Although there is plenty of meat on 

 these giant deep-sea prawns, fishing for 

 them in such deep watens would obviously not be profitable. But off 

 Natal, at a depth of between 500 and 600 metres, we caught quantities 

 of some large and palatable penaeid prawns. The attention of the South 

 African authorities was at once drawn to this prolific stock, which offers 

 facilities for profitable fishing. 



There are many bathypelagic squids and octopuses, some black, some 

 a deep purple, and some translucent. Light organs are common, especially 

 in the squids, and may occur in many places — on the body, the arms, 

 the head, or the eyes. They may be few or many in number and of various 

 types, primitive or highly complex. Most of the species are widespread 

 in the oceans, though some have been seen on only a few occasions. We 

 obtained several of these rare species. 



Noteworthy among the squids is the genus Chiropsis, distinguished 

 by its extraordinarily long arms. The single known species of this genus 

 had been found by the Dana Expedition in the Atlantic. We found ano- 

 ther in one of our deepest hauls, in the Kermadec Trench near New 

 Zealand. 



Another squid is the strange little Spirula spirula (Fig. above). This 



Spirula spirula, swimming. 



