Huddling behavior facilitates homeothermy in the naked mole rat Heterocephalus glaber

Naked mole rat is a highly social mammal, living in large underground colonies in equatorial Africa. Isolated naked mole rats exhibit unusual thermoregulation and cannot regulate body temperature (T_b). Thermoregulatory parameters, namely Vo₂, evaporative water loss (EWL), and T_b, were therefore examined when these animals were housed in groups ranging from 2-8 animals. Oxygen consumption at low ambient temperatures (T_a's), irrespective of the experimental group size, increased with increasing T_a in a poikilothermic manner. Changes in Vo₂ with increasing T_a switched to an endothermic pattern at T_a's ranging from 25°C (for groups of eight) to 27°C (for pairs). Huddling behaviour not only saves energy and water, so essential in an arid environment where food is sparsely distributed, but huddling also plays a very important thermoregulatory role in these otherwise nonendothermic mammals. Huddling ensures that, in their natural habitat, naked mole rats are able to control T_b and are indeed homeotherms. -from Authors