Further to the recent debates about thermoregulation, I thought this was pretty interesting. Apparently at least some snakes can create their own gradients
(Thanks to Allen Salzberg's HerpDigest- )
The Thermogenesis Of Digestion In Rattlesnakes.
Tattersall GJ, Milsom WK, Abe AS, Brito SP, Andrade DV.
J Exp Biol. 2004 Feb 1;207(Pt 4):579-585.
Department of Biological Sciences, Brock University, St Catharines, ON, L2S 3A1, Canada Department of Zoology, University of British Columbia, 6270 University Blvd, Vancouver, British Columbia, Canada, V6T 1Z4 Departamento de Zoologia, c. p. 199, Universidade Estadual Paulista, 13506-900, Rio Claro, SP, Brasil.
Some snakes have a feeding regime characterized by the infrequent ingestion of relatively large meals, causing impressive increments in post-prandial metabolism. Metabolism remains elevated for many days, while digestion proceeds, resulting in considerable investment of time and energy. Snakes actively adjust thermoregulatory behavior to raise their body temperature during digestion, exhibiting a post-prandial thermophilic response that accelerates digestion at the expense of higher metabolic rates. In the present study, we investigated the possibility that endogenously derived heat, originating as a byproduct of the post-prandial increase in metabolism, could itself contribute to the elevated body temperature during digestion in the South American rattlesnake Crotalus durissus. We assessed heat production, at a constant environmental temperature, by taking infrared (IR) images of snakes during fasting and after being fed meals varying from 10% to 50% of their own body masse!
s. Our results show clearly that digesting rattlesnakes have significantly increased body temperatures, even when precluded from adjusting their thermoregulatory behavior. The feeding-derived thermogenesis caused the surface body temperature of rattlesnakes to increase by 0.9-1.2 degrees C, a temperature change that will significantly affect digestive performance. The alterations in body temperature following feeding correlated closely with the temporal profile of changes in post-prandial metabolism. Moreover, the magnitude of the thermogenesis was greater for snakes fed large meals, as was the corresponding metabolic response. Since IR imaging only assesses surface temperatures, the magnitude of the thermogenesis and the changes in deep core temperature could be even more pronounced than is reported here.