94 



BIOLOGY OF THE SEAS OF THE U.S.S.R. 

 Table 32 



Group 



No. of species 



Group 



No. of species 



Radiolaria 



Infusoria 



Rhizopoda 



Coelenterata 



Vermes 



Rotatoria 



Mollusca 



Cladocera 



Total 151 



shallows. As a typically arctic component of plankton, one may mention 

 such forms as Appendiculariidae Oikopleura labradoriensis and O. vanhoeffeni. 

 As occurs in other seas, the main part of Barents Sea zooplankton consists of 

 Copepoda: in the southwest of the sea (V. Jashnov, 1940) they form almost 

 90 per cent of the biomass : moreover the most important of them is Calanus 

 finmarchicus which constitutes on average 30 per cent of the plankton bio- 

 mass. Of the other plankton components only Euphausiacea (5-3 per cent) 

 and Chaetognatha are prominent (3-2 per cent). All the others taken together 

 average not more than 3 per cent (by biomass). B. Manteufel (1941) thinks 

 that in the southwestern parts of the Sea at certain seasons of the year, 

 Euphausiacea may form about half of the whole plankton biomass. 



In sea inlets the relative number of Copepoda is smaller, and there is a 

 considerable admixture of Cladocera and Cirripedia larvae {Table 33). 

 The large number of Pteropoda is more or less accidental; in 1931 they were 

 very numerous (25 per cent of the biomass), and in 1932 they were entirely 

 absent. It is of interest to note that during both years of investigation in 

 Motovsky Gulf Calanus finmarchicus constituted about the same percentage of 



Table 33 



