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Two types of oogenesis have been observed among orders of the scyphozoan. In rhizostome and semaeostome species, the oocytes develop in close association with trophocytes, specialized gastrodermal cells that are though to have a nutritive function. In coronate species, oocytes develop freely within the mesoglea.... 顯示更多 Two types of oogenesis have been observed among orders of the scyphozoan. In rhizostome and semaeostome species, the oocytes develop in close association with trophocytes, specialized gastrodermal cells that are though to have a nutritive function. In coronate species, oocytes develop freely within the mesoglea. Oocyte development in Catostylus mosaicus appeared to be consistent with those of other rhizostomes, with oocytes remaining connected to the gastrodermis via tropocytes throughout development.
Like most scyphozoans, Catostylus mosaicus is gonochoristic. The sex ratio did not differ from 1:1 over 8 sampling times within a period of 1 yr. Sex ratios of scyphozoans are known to vary between 1:1 and 1.7 females:1 male. The sex ratio may also vary according to time of year. For example, in the Niantic River Estuary, female Cyanea sp. medusae outlive males so, at certain times of the year, the population consists entirely of female medusae. Although there was some variation in the sex ratio of C. mosaicus among months, the pattern was not consistent between consecutive months and there was no evidence if temporal trends in the frequency distribution of the sexes.
The sex of some scyphozoans can be determined from the presence of brooding structures in the females, such at the brood pouches on the oral arms of Aurelia aurita or the brood-carrying filaments of Cotylorhiza tuberculata. The colour of the gonads has also been used to differentiate between the sexes of the semaeostome Dactylometra quinquecirrha, with male gonads being bright pink and female gonads grayish brown or yellowish brown. There were no distinctive brooding structures on Catostylus mosaicus, and the colour of the gonads was not consistent between sexes. Consequently, sexes could only be differentiated by microscopic examination of gametogenic tissue. There were differences in the sizes of male and female medusae. Trends were not consistent among times, however, suggesting that there is no sexual dimorphism in relation to size.
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