Development of scyphozoan ephyrae (Cnidaria, Medusozoa) and their interaction with the fluid environment

Author(s)

Mayara de Almeida Jordano

• Document type: Master's Dissertation
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Instituto de Biociências (IBIOC/SB)
• Defense date: 2018-09-13

Examining board members

André Carrara Morandini; Gustavo Fernandes Camargo Fonseca; Sergio Nascimento Stampar

• Advisor: André Carrara Morandini; Renato Mitsuo Nagata

Abstract

The diversity of prey capture structures (tentacles and oral arms) in adult jellyfish is associated with different capture mechanisms and feeding habits. The understanding of these structures development can clarify the feeding mechanics and, consequently, increase the knowledge about the trophic consequences of the recurrent jellyfish blooms. However, few studies describe the capture structures initial development and their interaction with the fluid environment (i.e., Reynolds number, Re). The objective of this work was to describe the development stages in Rhizostomeae (Mastigias papua, Cassiopea sp., Cotylorhiza tuberculata, Catostylus townsendi, Catostylus mosaicus, Lychnorhiza lucerna, Phyllorhiza punctate and Rhopilema esculentum) and \"Semaeostomeae\" (Chrysaora plocamia and Aurelia cf. sp. 4) species, focusing on the bell and oral arms (chapter 1); to test the hypothesis that different temperatures during growth generate a differentiated development of the bell and oral arms, which would compensate for the boundary layer effect under low temperatures (i.e., low Re) for the effective functioning of these structures as collector filters (Chapter 2); to characterize the distribution of the ciliated epidermis and the flows produced in ephyrae and young jellyfish of Lychnorhiza lucerna, to measure the water layer thickness that the cilia can move and to calculate the Re around the digitata covered by cilia (Chapter 3). For this, the ephyrae were submitted to specific treatments and photographed until they were 35 days old and the transport of particles through the ciliary epidermis was filmed. We conclude that the initial development characterization of different strains of Scyphozoa ephyrae makes it possible to know the morphology of jellyfish, i.e., their swimming and feeding structures, thus providing an understanding of their functions. On the other hand, scyphomedusa showed to be resilient to the temperature variations, exhibiting a differentiated growth that must guarantee the maintenance of the swimming and food structures functions. The ciliary epidermis is present throughout the jellyfish and has moved a layer of water up to 0.28 mm. The ciliary stroke collaborates with the food mechanism with the transport of particles and acts on the dynamics of fluid mechanics by creating flows in the same direction of the flow generated by the bell contractions, helping to diminish the effect of the boundary layer. Finally, we highlight that this work showed the relevance of jointly studying the morphological development, behavior and fluid mechanics to comprehend in a complementary way the mechanisms underlying the food ecology of important marine predators such as Scyphozoa jellyfish (AU)

• FAPESP's process: 15/25142-8 - Temperature effect over ontogenetic patterns of feeding structures in scyphozoan ephyrae: functional and ecological implications
• Grantee: Mayara de Almeida Jordano
• Support Opportunities: Scholarships in Brazil - Master