Fig. 5. The risk to hatchling painted turtles of freezing by inoculation was assessed in animals that had just completed incubation at 27°C (unacclimated) and in neonates that were acclimated at a high temperature (24°C) or a low temperature (3°C). Turtles were placed individually into artificial nests where they came into intimate contact with moist soil. Water in the soil first was caused to freeze at a temperature above the equilibrium freezing point for bodily fluids of hatchlings, so turtles came into contact with ice before they were susceptible to freezing. Temperature then was lowered to -2°C, which is above the temperature at which hatchlings freeze spontaneously by heterogeneous nucleation, and this temperature was maintained for 7 days. Spikes (exotherms) in the temperature profiles yielded evidence for freezing by the turtles themselves. A malfunction of an environmental chamber caused background noise to be extraordinarily high in temperature profiles for unacclimated turtles, and some freezing exotherms consequently may have escaped detection. Indeed, all the animals for which no exotherm was detected (hatched bar in left column) are thought to have frozen. Letters displayed in italics above the bars are from one statistical analysis, and those within the bars are from another. Bars that share a letter from the same analysis cannot be distinguished statistically. Figure reproduced from Packard and Packard (2003b).