Comparative analysis of the gonadal structures of Cubozoa in the evolutionary context of Medusozoa (Cnidaria)

Author(s)

Jimena García Rodríguez

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Instituto de Biociências (IBIOC/SB)
• Defense date: 2024-03-12

Examining board members

Antonio Carlos Marques; June Ferraz Dias; Edgar Gamero Mora

• Advisor: Antonio Carlos Marques; Amanda Ferreira e Cunha

Abstract

Descriptive and comparative studies on sexual reproduction in Medusozoa, a diverse group of Cnidaria, are scarce, limiting the understanding of their evolution, especially regarding historical and functional patterns. This study sought to elucidate, through literature data and original data, histomorphological aspects of reproduction in four classes of Medusozoa Hydrozoa, Cubozoa, Scyphozoa, and Staurozoa exploring their varied reproductive strategies. Our objectives were: (1) to investigate the variation in oocyte size in Medusozoa species through a comparative approach; (2) to infer reproductive patterns of the box jellyfish Chiropsalmus quadrumanus from histomorphological descriptions of the gonads and oocyte development; (3) to elucidate reproductive patterns and oogenesis in Cubozoa, expanding the taxonomical base and using histomorphological data to explore novel reproductive characteristics. This study revealed unique and complex aspects of reproduction in non-bilateral animals. Among the main results, it was pioneering in demonstrating that egg size is a conserved characteristic with a significant phylogenetic signal in Medusozoa, influenced by both environmental factors, such as depth and temperature, and life history aspects, such as the number of eggs produced. We also proposed the first oocyte maturation scale based on histomorphological data for Chirodropida, and inferred iteroparity (continuous reproduction) and external fertilization in Chiropsalmus quadrumanus, based on the analysis of gonads and oocytes. Additionally, we described novel characteristics associated with the reproductive structures of Cubozoa, including the presence of hexagonal oocytes, internal fertilization of the gonad, autosynthetic synthesis of yolk from possible accessory nuclei, and the occurrence of nematocysts and nematoblasts within the gonads, suggesting the gonadal tissue (gastroderm) as a possible site of nematogenesis. This investigation enriched and qualified knowledge about the diversity and complexity of Medusozoa, especially concerning sexual reproduction and its reproductive attributes. The new evidence brought by this study adds complexity to the understanding of reproductive characteristics and life history of Cubozoa, broadening the perspective on their ecology and evolution in the marine environment. (AU)

• FAPESP's process: 19/01370-2 - Comparative analysis of the gonadal structures of Cubozoa in the evolutionary context of Medusozoa (Cnidaria)
• Grantee: Jimena Garcia Rodriguez
• Support Opportunities: Scholarships in Brazil - Doctorate