ON THE NEMATOCYSTS OF THE VARIOUS STAGES OF DEVELOPMENT OF RHOPILEMA ESCULENT A KISHINOUYE (CNIDARIA, SCYPHOZOA)

The nematocysts of the stages of planula,scyphistoma,strobila,ephyra,young medusa and matured medusa of Rhopilema,esculenta are examined with a light microscope.Three categories of nematocysts including four types are identified.They are a-isorhizic haplonemes (a-isorhizas),ovate anisorhizic haplonemes (o-anisorhizas),ellipsoidal anisorhizic haplonemes (e-anisorhizas) and heterotrichous microbasic eurytele (eurytelc).However,nematocysts have not been found in early planula.a-isorhizas and euryteles are both present in late planula and scyphistoma,while a-isorhizas,ovate anisorhizas and euryteles are found in strobila and ephyra.In addition,there is a new type of nematocysts,ellipsoidal anisorhizas,found in the lappets of some young medusae and matured medusae.It is a feature differing from the closely related species Rhopilema verrilli that the Rhopilema esculenta has an ellipsoidal anisorhizas type of nematocysts.It is the first time that nematocysts of this species are reported.