NO. 1 HARTMAN, BARNARD: BENTHIC FAUNA OF DEEP BASINS 17 



Some species have been taken only in nonreproductive or vegetative 

 stages; they may be incapable of attaining gonadial development at the 

 level of the basin floors. Such individuals can have had their ontogenesis 

 from reproductive populations typically existing at the sill or shallower 

 levels. Others that occur as adults or ovigerous are believed to be typical 

 at the basin level or in deeper parts of the ocean. 



Among the polychaetes, many species have a wide vertical or eury- 

 bathic range in the eastern Pacific and geographically into far northern 

 waters, suggesting a tolerance to depth and an adequate means of dis- 

 persal. Other species are strictly endemic and are not known outside of 

 these restricted ranges. Those taken by the ALBATROSS in 1904 

 (Appendix I) were all unknown when described. Fifty years later the 

 VELERO IV has taken many of the same species from similar or near- 

 by localities, as well as many other species which are considered to be 

 new to science and restricted in their ranges. A few of these species show 

 similarities with deep water forms taken in other parts of the world. 

 Many belong to genera with wide geographic ranges. Typical deep sea 

 animals having a reported cosmopolitan distribution were not identified 

 (IUBS, 1954). 



Food habits. Animals existing in the deep basins are mainly sedentary 

 or nonforaging in their feeding habits. Most of them rely on food which 

 is either brought to them or is in easy access. Exceptions to this may be 

 the brissopsid urchins, which burrow in the sediments, and the comatulid 

 crinoids, which move about more or less freely. Food requirements of 

 vegetative individuals can be very low, while actively growing or re- 

 producing stages have a high rate of consumption. The rain of organic 

 debris from the photosynthetic layers of the sea to the bottom must be 

 of small extent at depths such as exist in the basins. If higher dissolved 

 oxygen values existed in the shallow nearshore basins, they would be 

 more productive than the deeper basins; but the reverse appears to be 

 the case. Dead biological remains are much richer in the shallow basins, 

 while samples from deep basins rarely yield such debris. 



Some food in the basins may be provided by the straying of bathy- 

 pelagic life across the sediments, suggested by the occasional presence of 

 an otolith or fish scales. Limited food cycles occur as a result of reactions 

 between individuals of an association, the more voracious or larger, 

 devouring the lesser or smaller ones. The sills and banks surrounding 

 the basins are the habitats of considerable life. Animals at these depths 

 may partly supply the deeper floors with food in the form of larvae and 

 offal ; however, some of the larvae survive to repopulate and form vegeta- 

 tive components of the subsill faunas. 



