CHAPTER 12 

 Ecology 



The contemporary Pogonophora are apparently no mere fragments of a 

 formerly rich group which has become almost extinct. Until recently this 

 might have seemed a reasonable point of view, but oceanographic expeditions 

 are discovering new species of Pogonophora each year, from the Pacific Ocean 

 [and elsewhere] and the group seems to be a flourishing one consisting pre- 

 eminently of abyssal forms. They are enormously abundant in places. In 

 certain well investigated spots in the northwest Pacific Ocean trawling brings 

 up masses of inhabited and empty pogonophoran tubes, which may clog the 

 trawl bag and dangle from the frame and bridles. [Hartman (1961), in a 

 quantitative haul off the Californian coast found a density of Siboglinum 

 veleronis of 200/m 2 ]. If we can judge from the abundance of inhabited and 

 empty pogonophoran tubes mixed with mud they play an important role in 

 the benthos of many parts of the abyss. The majority of Pogonophora are 

 inhabitants of abyssal or hadal depths, of which they are especially charac- 

 teristic, but many species may be encountered also in comparatively shallow 

 places. Out of the 44 known species*, 25 (58 per cent) have been found at 

 depths greater than 3000 m. Of these only 9 species dwell also at shallower 

 horizons and 16 species (37 per cent of the total described species) have not 

 been found at depths less than 3000 m. A few forms, however, dwell in the 

 bathyal or even sublittoral zones. Such species, among others, are charac- 

 teristic of the Sea of Okhotsk. It is interesting to note that some of these 

 shallow water forms are encountered also in abyssal depths. Sixteen species 

 of pogonophores are known from depths less than 1000 m, 11 of which are 

 not encountered below the 1000 m line, but a few species (e.g. Oligobrachia 

 dogieli and Siboglinum caulleryi) possess a wide vertical distribution, going 

 down to depths of more than 2000 m. S. caulleryi in particular invites com- 

 ment, for it is able to live in shallow water in the Sea of Okhotsk (even as 

 shallow as 22 m), but it has also been found in the Kuril-Kamchatka Trench 

 at a depth of 8164 m. [I believe this is the greatest known bathy metric range 

 of any species of marine organism — D.B.C.] 



Ten of the known pogonophoran species are encountered in the greatest 

 depths of the sea, dwelling below the 5000 m line, and eight of them are 



* This was written in 1959. 



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