Composition and Distribution of Macrobenthic Invertebrate Fauna 105 



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INDIVIDUALS 

 PER SQUARE METER 



SIPUNCULIDA 



Figure 81 



Geographic distribution of Sipunculida: A — number of specimens per square meter of 

 bottom; B — biomass in grams per square meter of bottom. 



than 50 m the percentage of occurrence ranged from 

 21 to 32%, with the highest rates occurring at depths 

 < 1,000 m and the lower rates at depths > 1,000 m. 



Relation to Sediments 



Sipunculids inhabited all sediment types and occurred 



in about the same density in each type (Table 16; Fig. 



84). The range in average density in the various types of 

 bottom sediments was from 4.0 to 7.1/irr. Sand con- 

 tained the highest density. 



Biomass of sipunculids in relation to various sedi- 

 ment types was considerably more varied than density 

 of sipunculids (Table 18; Fig. 84). Biomass ranged from 

 low values (0.16 to 0.29 g/m 2 ) in shell and till sub- 



