Torpidity - It is the reduction of body metabolism, by controlled low oxygen consumption rates and lower body temperatures. It is accurately the control of metabolism which is restricted to warm-blooded animals. There is a different physiology in cold-blooded animals in response to adverse conditions. In some animals the state of torpidity is the response to lack of food and environmental conditions. Some species show seasonal torpidity. In the Northern states hibernation is the form. Aestivation is the kind of torpidity seen in very hot and dry conditions.
Animals in the cold climate undergo metabolic changes that allow them to sleep. Hibernation is the controlled, reduction in the rate of metabolism in the winter. The body temperatures of these animals are maintained a few degrees higher than the temperature of the environment. Most of the hibernating animals are small animals that have usually a high rate of metabolism. Animals wake up from hibernation during the late winters or early spring as they maintain only sufficient amount of reserved fat to carry them through the winter season.
In case of the bears they do not hibernate actually. Their body temperature drops for only a few degrees and the rate of metabolism is reduced only to moderate rates. Bears give birth in the winters; bears can be easily aroused in winter and then drop back into the state of dormancy.
In cold blooded animals dormancy is the reduced state of metabolic activity which is controlled by environmental conditions. Cold-blooded animals become dormant during winter and they lack to control the internal environment of their body. Many animals move to sheltered places and they also undergo chemical changes to prevent their tissues from freezing. Some animals’ can tolerate certain levels of ice between their cells with common chemical changes.
Insects undergoing dormancy in winter show specialized chemical adaptations to survive. Some insects have the ability to resist freezing and some can tolerate freezing to certain temperature.