60 



50 



40 



30 



20 



10 



SlZE(mm) 



Figure l.--Size frequency distributions of discs of the three fissiparous 

 brittle stars at Discovery Bay (August 1981). 



contain ripe gonads, and of 

 mm, 57 were female (23%). 

 this study, 11 with disc di 

 gonads. Of the 11, 2 with 

 females, 3 with disc diamet 

 remaining 6 were unsexable 

 Discovery Bay sites contain 

 have shown that at the Bogu 

 coast, 0^_ savignyi achieved 

 disc diameters greater than 

 sexual reproduction. The 

 in diameter, and the larges 

 roughly 10,000 eggs. 



246 animals with disc diameters greater than 2.0 

 Of the 56 specimens of 0. isacanthum examined during 

 ameters greater than 2.7 mm had recognizable 

 disc diameters of 3.6 and 3.3 mm were mature 

 ers of 3.5 and 2.8 mm were mature males, and the 



None of the 0. savignyi examined from the 

 ed gonads (table 3) , but Emson and Wilkie (1984) 

 e Islands in Montego Bay on the Jamaican north 

 a larger size (up to 5.5 mm) and specimens with 

 4.0 mm may contain ripe ova and achieve successful 

 argest oocytes in these specimens measured 0.10 mm 

 t individual (5.5mm disc diameter) contained 



The three fissiparous species are similar in producing small eggs within 

 the size range (0.07-0.20 mm) regarded as resulting in planktotrophic larvae 

 (Hendler, 1975; Mladenov, 1979). 



Since disc size and egg size are similar in the three species, it is not 

 surprising that reproductive output, as measured by maximum number of eggs 

 produced, is roughly equivalent (table 3). The maximum egg number for these 

 species is two to three orders of magnitude lower than that recorded for nonfis- 

 siparous brittle stars with planktotrophic development (Hendler, 1975; Mladenov, 

 1979; Mladenov and Emson, 1984). Compared to their nonf issiparous planktotrophic 



94 



