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| Author(s): |
Tábata Elise Ferreira Cordeiro
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | Ribeirão Preto. |
| Institution: | Universidade de São Paulo (USP). Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto (PCARP/BC) |
| Defense date: | 2019-12-05 |
| Examining board members: |
Wilfried Klein;
Kênia Cardoso Bícego;
Adriano Bonfim Carregaro;
Marisa Narciso Fernandes;
Tiana Kohlsdorf;
Marina Rincon Sartori
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| Advisor: | Wilfried Klein |
| Abstract | |
Testudines perform intermittent pulmonary ventilation, a convenient process since it reduces energy expenditure, especially in aquatic species. Some species of aquatic turtles are also able to perform gas exchange with water, using the skin, buccopharyngeal epithelium and/or the cloacal bursae as gas exchange surfaces. Phrynops geoffroanus possesses lower rates of ventilation and oxygen consumption in air when compared to other turtles, suggesting a bimodal gas exchange strategy in this species. This work, therefore, aimed to understand the mechanisms of gas exchange in Phrynops geoffroanus, testing the hypothesis that the species possesses extrapulmonary tissues capable of absorbing oxygen from the aquatic environment. To answer this question, an integrative approach was chosen, investigating the working hypothesis using different methods, considering behavioral, morphological and physiological aspects. Additionally, the first chapter of this thesis presents the proposal of an anesthetic protocol for use in physiological experiments. The combination of ketamine (40mg.kg-1) and midazolam (2 mg.kg-1) proved to be an effective anesthetic combination allowing short-term surgical procedures in P. geoffroanus. Within the behavioral approach, we observed that P. geoffroanus was able to spend long periods submerged and that most of the time the animals remained at rest. The morphological analyzes of the integument, the bucopharyngeal cavity, the cloacal bursae and the lungs ruled out the possibility of aquatic gas exchange occurring through skin and mouth. Morphometric analyzes showed that mass-standardized volume density and respiratory surface area were significantly greater in the lungs than in the cloacal bursae. Physiological experiments confirmed that P. geoffroanus was not able to absorb oxygen through the buccopharyngeal cavity and cloacal bursae, even under conditions of aquatic hyperoxia. It is therefore concluded from the present data that P. geoffroanus does not perform extrapulmonary gas exchange in proportions adequate for the maintenance of the basic metabolic needs of the species, as the different approaches employed here, behavioral, morphological and physiological, did not provide any support for a bimodal gas exchange strategy in this species. (AU) | |
| FAPESP's process: | 16/17200-0 - Bimodal breathing strategy in Phrynops genus (Wagler, 1830) and Chelus fimbriata (Schneider, 1783) |
| Grantee: | Tábata Elise Ferreira Cordeiro |
| Support Opportunities: | Scholarships in Brazil - Doctorate |