235 



Figure 183: Stichopus japonicus. 



Arrangement of coelomic sacs and diverticulae in the auricularia before metamorphosis. 



cd — coelomic diverticula; he — hydrocoel; Is — left somatocoel; pv — polian vesicle; 



rs — right somatocoel. 



the lowermost band is formed through the fusion of the remains of the band 

 of the p6sterolateral processes. The band lying above them is formed from the 

 two fragments of the band of the posterodorsal processes and the two frag- 

 ments of the band of the anal lobe. The medial band is formed from areas 

 of the band of the mediodorsal processes; the band lying above them is 

 formed from two parts of the band of the anterodorsal processes and one part 

 of the band right of the preoral lobe. The uppermost band is formed from the 

 parts of the band of the oral zone of the larva and the left side of the preoral 

 lobe (Kume and Dan, 1968). 



Formation of the cilliated bands of the doliolaria proceeds fairly rapidly; 

 in Stichopus japonicus it takes 30-36 hrs. Formation of the doliolaria is the 

 turning point in the life of a sea cucumber larva since metamorphosis begins 

 from this stage. 



