Body Temperatures of Reptiles

Abstract

A summary of body temperatures of reptiles has been made on the basis of some 9000 body, air, soil, and water temperatures taken or recorded in the literature for 161 species of reptiles. The range and mean body temperature for the various groups of reptiles are: turtles: 8.0 to 37.8, mean: 28.4; Sphenodon: 6.2 to 18.0, mean: 12.5; American alligator: 26-37, mean: between 32 and 35; snakes: 9.0 to 38.0, mean: 25.6; lizards: 11.0 to 46.4, mean 29.1. There are often specific, generic, and family differences in thermal tolerances and preferences, though some reptiles show wide ranges of thermal tolerance with no "preferred" body temperature, while others have narrow activity ranges and preferences. With an increase in thermal preference, there is usually an associated increase in the critical thermal maximum. Forms with low thermal preference usually have low critical minima and are usually found in colder areas and in colder seasons than those with high thermal preferences. In terms of their thermoregula-tory behavior, reptiles can be grouped into: burrowing forms; aquatic forms not selecting temperatures; aquatic forms selecting temperatures; aquatic forms which bask at surface or on shore; nocturnal thigmo-thermic forms; nocturnal thigmothermic forms that occasionally bask; diurnal, primarily thigmothermic forms that occasionally bask and become crepuscular or nocturnal as hot seasons develop; diurnal non-baskers; diurnal limited baskers; and true heliothermic baskers. Thermo-regulation in reptiles is both behavioral (emergence, retreat, selection of temperatures, basking, orientation, postural changes, etc.) and physio-logical (evaporative cooling, vasomotor responses affecting rates of heating and cooling, and limited heat production in brooding female Indian phythons).