Behavioral thermoregulation in the salamander Necturus maculosus after heat shock

1. 1. Adult salamanders were acclimatized to 15 ± 1°C and an LD 12:12 photoperiod and divided into three groups: (A) heated to the critical thermal maximum (CTM, onset of muscular spasms; 33.74 ± 0.13°C); (B) heated to 2.75 ± 0.07°C below the CTM; (C) controls, not heated. 2. 2. All three groups were placed in linear thermal gradients (5–30°C) and deep body temperatures recorded with thermocouples every 30 min for a 3-day period. 3. 3. Both CTM and sub-CTM groups had significantly higher initial selected temperatures than controls, followed by a gradual decline. The initial selected temperatures of the sub-CTM group were higher than the group exposed to the CTM. 4. 4. Normal diel cycles in body temperatures displayed by control animals were eliminated in the two experimental groups.