Full text
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| Author(s): |
Daniel Rodrigues Stuginski
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Instituto de Biociências (IBIOC/SB) |
| Defense date: | 2009-05-12 |
| Examining board members: |
Augusto Shinya Abe;
Denis Otavio Vieira de Andrade;
Jose Eduardo Pereira Wilken Bicudo
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| Advisor: | Augusto Shinya Abe |
| Abstract | |
The study of the preferred temperatures and thermophilic behavior is essential to understand the snakes thermal biology. Although some studies have been reported, most of them are focused in temperate and diurnal species. Thus, little is known about the tropical and sub-tropical nocturnal species. In the present study , a video-monitored arena with a thermal gradient was used to investigate the preferred thermal range during activity and inactivity (Tset) and the post-prandial thermophilic response after different levels of food intake in 29 Brazilian lanceheads (Bothrops moojeni). The results showed that the preferred thermal range of B.moojeni changes depending on the photoperiod (20.93°C to 22.20°C in daytime and 22.81°C to 24.42°C in night time), being similar to other crotalinae snakes. Our data suggests that there is an inverse correlation between the post-prandial thermophilic response intensity and food intake, as animals fed with a portion corresponding to 10% of its bodyweight presented a higher thermophilic response in comparison to those who were fed with larger portions (20 and 40% of bodyweight). This difference may be related to the decreased mobility and increased SDA (Specific Dynamic Action) in animals that consumed the largest amount of food. Crotalinae are considered to be mainly nocturnal and most of the gathered data on these snakes came from field work. The knowledge of activity pattern and how nutritional status affect wandering rate are determinant to understand the ecophysiology of the snakes. In this study the daily activity pattern was followed in 29 subjects of the lancehead Bothrops moojeni in order to record displacement rate in fasting and feed snakes for five days after feeding meal of 10, 20 and 40% of their own body weight. The results show that B.moojeni is prevalently nocturnal, and activity increased 45 times at night, peaking between 19 to 20 h, in both males and females. Activity level changed significantly after feeding in snakes which ate a larger meal (20-40%). The results confirm previous field data for B.moojeni as a nocturnal species with low mobility. The complex interactions between the amount of food taken by the snake, energetic balance and mobility are discussed. Snakes were for long considered incapable to generate heat fueled by aerobic metabolism, except for brooding pythons. However, recent studies proved that some species are able to elevate their body temperature without muscle contraction or external heat source. Such thermogenic capacity is supported by high metabolic rate that follows digestion and assimilation of food (Specific Dynamic Action - SDA). Snakes have a low maintenance cost and most species can stand for long fasting time, particularly after ingesting a great meal. The energy produced during digestion of such meal can generate significant increase in body temperature. The present study investigated thermogenic response after feeding in the Brazilian lancehead, Bothrops moojeni, using thermal images taken in temperature controlled environment at 30°C. The 12 snakes were divided into two groups and followed for 72 hours after fed a meal representing 10-20% and 30-40% of their body weight, respectively. The results showed thermogenic digestive response with an increase up to 1.6 °C of skin temperature. Thermal heat production peak occurred between 33 to 36 hours after feeding in both groups, and the duration of thermogeny varied with the meal size. The result showed high correlation between thermogenic data and SDA in snakes. The significant increase of body temperature after feeding and its maintenance for extended time suggest a physiological advantage to keep high metabolic rate despite of environmental temperature. (AU) | |