Nc. Bennett et al., THERMOREGULATION AND METABOLIC ACCLIMATION IN THE NATAL MOLE-RAT (CRYPTOMYS HOTTENTOTUS NATALENSIS) (RODENTIA, BATHYERGIDAE), Zeitschrift fur Saugetierkunde, 58(6), 1993, pp. 362-367
The social Natal mole-rat Cryptomys hottentotus natalensis has a mean
(+/- S.D.) resting metabolic rate (RMR) when newly captured of 1.03 +/
- 0.25 cm(3) O-2 g(-1) h(-1) (n = 7) at an ambient temperature (Ta) of
30 degrees C, within the thermoneutral zone (TNZ) of 30-31.5 degrees
C. Two months after maintenance in the laboratory at 26 degrees C, the
RMR of the same animals showed a concomitant drop in value of 20 % at
30 degrees C (TNZ) to a mean of 0.80 +/- 0.12 cm(3) O-2 g(-1) h(-1) (
n = 14), indicating that la6oratory acclimation had occurred. The body
temperature of the mole-rat is low 33.4 +/- 0.83 (n = 36) and remains
stable at Ta's from 10-30 degrees C. Above 31.5 degrees C, Tb increas
es albeit slightly to 35.7 +/- 0.51 degrees C (n = 24). The conductanc
e is high 0.13 +/- 0.03 cm(3) O-2 g(-1) h(-1) degrees C-1 (n = 24) at
the lower limit of thermoneutrality. The mean RMR at 18 degrees C (the
lowest Ta tested) was 1.83 +/- 0.46 cm(3) O-2 g(-1) h(-1), which is 2
.2 times that of the RMR in the TNZ. The nest (where mole-rats rest fo
r up to 80 % of the day) is the focal point of the burrow system. The
selection for C. h. natalensis to acclimate within its TNZ may relate
to seasonal fluctuations in the temperature occurring in the shallow n
est, resulting in seasonal acclimatisation in RMR.