Table l.--The frequency of fertile polyps in four colony size classes of 

 Z. sociatus and Z. solanderi . Colonies were collected in June, 1983, 

 at Discovery Bay, Jamaica. Numbers of colonies are given in parentheses. 



Colony 



size 



class 



Polyp 

 condition 



Z. sociatus 



Z. solanderi 



A. < 20 polyps 



B. 20 < 40 polyps 



C. 40 < 60 polyps 



D. very large 

 (subsamples 

 = 50 polyps 

 per colony) 



E. < 60 polyps 

 very large 



ferti le 

 nonferti le 



fertile 

 nonferti le 



fertile 

 nonferti le 



ferti le 

 nonferti 1 e 



ferti le 

 ferti le 





 227 (N=31) 





 103 (N=4) 





 58 (N=l) 



105 



395 (N=10) 



(N=36) 

 105 (N=10) 



8 9.44 



188 (N=40) p < 0.005 



22 22.12 



92 (N=4) p < 0.001 



9 11.63 



40 (N=l) p < 0.001 



179 26.93 



321 (N=10) p < 0.001 



39 (N=45) 21.36 

 179 (N=10) p < 0.001 



observed to fragment either as clusters of loose polyps, analogous to the "polyp 

 balls" reported by Rosen and Taylor (1969), or as polyps attached to shifting 

 rubble. The fact that fragmentation occurs, however, does not demonstrate that 

 it is adaptive or an important life history characteristic. 



The frequency of fertile polyps in ten extremely large colonies of Z. 

 sociatus and Z. solanderi was 21% and 36%, respectively (table ID). These were 

 sampled during their peak reproductive season, as indicated by Karlson (1981, 

 and unpub. data). None of the polyps in 36 small colonies (< 60 polyps) of Z. 

 sociatus were fertile; 11% of the polyps in 45 small colonies of Z. solanderi 

 were fertile (table IE). All three small colony size classes exhibited 

 significantly higher frequencies of fertile polyps for Z_^ solanderi than for Z. 

 sociatus (table 1A, B, and C). The absence of fertile polyps in small Z. 

 sociatus colonies suggests that this species delays sexual reproduction while 

 Z. solanderi does not. 



Further examination of the 81 small zoanthid colonies (< 60 polyps) 

 revealed another significant difference between these two species. Colonial 

 growth in zoanthids commonly occurs by the budding of new individuals from 

 stolons. These stolonal connections can degenerate over time (West, 1979), 

 resulting in very loosely organized colonies with extremely low levels of 

 integration and asynchronous sexual reproduction (e.g., table ID). As a measure 



19 



