PELAGIC COMMUNITIES 319 



more numerous in the layer above 150 meters." Beebe and Hollister 

 record numerous shrimp jelly fishes and fishes in great numbers, as 

 • seen from the bathysphere. 



Two associations are suggested for this community. One, the 

 southern, characterized by fishes of the genera Valenciennellus and 

 Ichthyococcus ; another, more northerly, typified by Stomias boa 

 (Murray and Hjort). 



Fish-Tunicate Community (Myctophum-Salpa Biome) 



This community occurs from to 150 meters and lies south of the 

 Wyville Thompson Ridge. It is characterized by numerous animals 

 such as Foraminifera, Radiolaria, Copepoda, and pteropods, and mi- 

 croscopic plants, chiefly diatoms which are most abundant at 10-20 

 meters and scarce below 100 meters (Gran, 1912). The larger pre- 

 dominant animals include jellyfishes, the Portuguese man-of-war 

 (Physalia), quantities of compound tunicates (Salpa) (cf. Brooks, 

 1893) and numerous scopelid fishes, e.g., seven species (Myctophum) 

 which are of outstanding importance. The animal grouping also in- 

 cludes cephalopods belonging to seven genera. Sperm whales and cer- 

 tain right and hump-back whales occur. The color characteristics of 

 the community are illustrated by "the minute young of Scombresox 

 living at the very surface, the sides of which are mirror-like, while 

 the backs are intense blue. One group containing seablue forms is 

 represented by the flying-fish. The pilot-fish are also blue, but with 

 some darker transverse bars. In the surface layers most animals are 

 colorless. The eel larvae (Leptocephali) are indeed so transparent 

 that one can only see their small black eyes; even their blood is trans- 

 parent and devoid of haemoglobin" (Murray and Hjort, loc. cit., 669- 

 670). 



Mackerel-Calanus Community (Scomber-Calanus Biome) 



A pelagic community of rather wide distribution in the colder 

 waters of the North Atlantic is suggested in Bigelow's account (1924, 

 a, b) of the plankton of the Gulf of Maine and the work of IVIurray 

 and Hjort on the Norwegian Sea. It is characterized by a great abun- 

 dance of Calanus finmarchicus as the most abundant and uniformly 

 distributed copepod associated with other copepods, Sagitta, jelly- 

 fishes, etc., mackerel (Scomber scombrus L.), herring (Culpea species), 

 and whales of the genera Balaenoptera and Megaptera, which feed 

 upon fishes and pelagic crustaceans. This community appears to exist 

 in the upper 150-200 meters. It illustrates the principle found to 



