720 



DEPTHS OF THE OCEAN 



Abundance 

 of minute 

 Crustacea in 

 various areas 

 and depths. 



food of copepoda in deep water has not yet, as far as I know, 

 been made the subject of systematic investigation, although this 

 point is essential to a more complete understanding of marine 

 biology. Nordgaard, who is describing the copepoda from our 

 Atlantic cruise, has at my request been kind enough to examine 

 the stomachs of a large number of copepoda from our deepest 

 hauls in the Sargasso Sea, but has not been able to find any- 

 thing morphologically definable in their stomach-contents. Do 

 these copepoda there feed on detritus formed by the dead and 

 disintegrating organisms falling from the surface of the ocean ? 



Along with other small animals (foraminifera, radiolaria, 

 sagittidae), the copepoda and other Crustacea form the main 

 food -supply for the majority of the somewhat larger oceanic 

 animals. Thus the stomach-contents of the pteropods Clio 

 falcata and Lmiacina helicoides taken at depths between 500 

 and 1500 metres consisted of foraminifera and radiolaria. In 

 the stomachs of large prawns, Acanthephyra purpurea and 

 A. multispma taken below 500 metres, Sund found the remains of 

 copepoda, sagittidae, and fragments of minute fishes (Cyclotkone). 

 Koefoed has examined numerous stomachs of Cyclotho7ie without 

 finding any contents, but their guts contained organic remains, 

 mainly the jaws of minute crustaceans. The stomach of the 

 fish Gonostoma grande from deep water was found to contain a 

 mysid [E?t-copia austi^alis), and in Gonostoma rhodadenia were 

 found five euphausidse i^Nematosceiis, Siylockeiron, Eiphausia, 

 Thysanopoda), seven sagittae, five copepoda (Btuhceta, Buca/amis), 

 and some lumps consisting of radiolaria. 



Many of the pelagic fishes are extremely voracious. 

 Repeatedly other fishes have been found in their stomachs of 

 a size nearly equal to that of the devourer. Thus a small 

 Astronesthes niger had a scopelid in its stomach, and a 

 Chauliodus had eaten a Stomias boa. The record for voracity 

 is held by the remarkable Cliiasmodus niger (of which we 

 took three specimens in the Atlantic), which is known to 

 swallow fishes several times its own size. Fig. 514 shows a 

 specimen with only slightly extended abdomen; Fig. 515 

 shows a specimen that has swallowed a fish much larger than 

 itself, and most strangely one of the same species. 



Generally speaking, the very minute animals, especially the 

 minute Crustacea, play an exceedingly important part as 

 nourishment for other and larger animals. These minute 

 crustaceans are constantly taken in the fine silk tow-nets, and 

 in nets with a somewhat larger mesh they constitute the bulk 



