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| Author(s): |
Gisele Rodrigues Tiseo
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Instituto de Biociências (IBIOC/SB) |
| Defense date: | 2022-05-06 |
| Examining board members: |
André Carrara Morandini;
Maria de Los Angeles Mendoza Becerril;
Elizabeth Gerardo Neves;
Agustín Schiariti
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| Advisor: | André Carrara Morandini |
| Abstract | |
Among Medusozoa, the class Scyphozoa is one of the four that composes the subphylum with 241 described morphospecies. Its representatives are commonly called true jellyfishes and are currently divided into two subclasses: Coronamedusae and Discomedusae. Coronamedusae is known to have deep-sea species, but the diversity of the group (57 described species) also includes shallow-water species. The subclass Discomedusae has 184 species divided into two orders: Semaeostomeae and Rhizostomeae, and their representatives are known to be planktonic with a biomass of up to 96% of water. Although sexual reproduction in Scyphozoa has received relatively considerable attention over the years, there are few studies relating the characteristics related to jellyfish gonads in a comparative and phylogenetic context. This thesis brings new morphological data on sexual reproduction of scyphozoans and, comparatively, identifies relevant evolutionary patterns for future support in the classification of the taxa. In chapter 1 we review the state of the knowledge of sexual reproduction in coronate medusae, bringing new microscopic data from the gonads and discussing the main evolutionary trends for the group. In chapter 2 we describe the microscopic structure of the gonad in Scyphozoa, spermatogenesis and sperm ultrastructure in three species of discomedusae and discuss the similarity of the histological organization of the male gonad with the seminiferous tubule found in other metazoans. In chapter 3 we present data on the oogenesis of the semaeostomeae Chysaora lactea discussing the important roles played by trophocytes during vitellogenesis, choriogenesis and spawning. In chapter 4 we review gametogenesis for semi-sessile jellyfish of the genus Cassiopea, reporting a case of hermaphroditism in C. frondosa. Finally, in chapter 5 we review and compare the macroscopic, histological and cellular organization of the scyphozoan gonads, discussing the main topics and evolutionary novelties related to the sexual reproduction of the class Scyphozoa. (AU) | |
| FAPESP's process: | 17/12970-5 - Sexual reproduction in jellyfish species (Scyphozoa, Cnidaria) of Southeast Brazilian coast |
| Grantee: | Gisele Rodrigues Tiseo |
| Support Opportunities: | Scholarships in Brazil - Doctorate |