THE DISTRIBUTION OF POLYCHAETES WITHIN THE 



INDO-PACIFIC 



By G. A. Knox 



Biology Department 



Canterbury University College 



Christchurch, New Zealand 



Polychaetes have not generally been regarded as being useful for 

 the delimiting of zoogeographical regions. European workers when 

 working up the results of collections from other regions were struck 

 by the large percentage of European species that occurred among the 

 material they studied. The percentage of cosmopolitan species in many 

 regions is high when compared with other animal gioups. In one of 

 the areas involved in this study, 40% of the species can be classed as 

 cosmopolitan. If these cosmopolitan species are eliminated from the 

 lists a much clearer picture of the faunal relationships is obtained. 



The majority of studies on Polychaete distribution have lumped 

 together the shelf, benthal deep-sea, and pelagic faunas when consider- 

 ing relationships. In this study as far as jDOSsible only the shelf fauna 

 has been considered. Difficulties were encountered as a large number 

 of Polychaetes are eurybathic and species occurring only in deep water 

 in one locality may also occur on the shelf. This is the first attempt 

 to assemble distribution records for the polychaete fauna for "an area 

 as large as the Indo-Pacific. Wesenburg-Lund (1949) has recently sum- 

 marized the distribution records for the Persian Gulf, Arabian Sea and 

 Indian Ocean; and the relationships of the faunas of the East Indies, 

 Philippines, Japan, Australia and New Zealand have been discussed by 

 workers on collections made in these regions. 



In such a survey as this there are so many difficulties that only 

 very general conclusions concerning the nature of the distribution can 

 be reached. In the first place in many areas there has been relatively 

 little collection done. This applies particularly to the Pacific Islands. 

 In the second place many of the collections have been selective rather 

 than representative. From Table I it will be seen that from many 

 areas a large number of Families are unrepresented. This applies par- 

 ticularly to small inconspicuous species such as the Syllidae. Some 30 

 species of Syllids have been recorded from the eastern temperate shores 

 of Australia, while only two have been recorded from the adjacent tro- 



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