A Comparative Study of Time Constants of Cooling in Green Tree Frogs (Hyla cinerea) and Southern Leopard Frogs (Rana sphenocephala)

Thermal time constants were determined for an arboreal frog, Hyla cinerea, and a semiaquatic frog, Rana sphenocephala, exposed to a step-change in air temperature from 30-15 C. Mean time constants and equilibrium body temperatures were significantly greater and area-specific cutaneous evaporative wa...

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Bibliographic Details
Published in:Herpetologica 1988-09, Vol.44 (3), p.261-265
Main Author: Wygoda, Mark
Format: Article
Language:English
Subjects:
Amphibians
Biological and medical sciences
Body temperature
Cooling
Cross cultural studies
Freshwater
Frogs
Fundamental and applied biological sciences. Psychology
Herpetology
Hyla cinerea
Rana sphenocephala
Reptiles
Surface areas
Thermoregulation. Hibernation. Estivation. Ecophysiology and environmental effects
Time constants
Vertebrates: anatomy and physiology, studies on body, several organs or systems
Water loss
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Summary:Thermal time constants were determined for an arboreal frog, Hyla cinerea, and a semiaquatic frog, Rana sphenocephala, exposed to a step-change in air temperature from 30-15 C. Mean time constants and equilibrium body temperatures were significantly greater and area-specific cutaneous evaporative water loss rates significantly lower in the arboreal species. There was a strong correlation between thermal time constant (τ, in minutes) and body mass (M, in grams) for both species. The slope of the body mass regression equation for H. cinerea$(\tau =2.82{\rm M}^{0.57})$was not significantly different from that for R. sphenocephala$(\tau =2.14{\rm M}^{0.44})$, but the intercepts differed significantly. Prolonged cooling may be adaptive in maintaining elevated body temperatures as ambient temperature decreases.
ISSN:0018-0831
1938-5099