Ectothermy

All physiological and biochemical processes including immune function are temperature-dependent. Mammals have a constant core body temperature range but snakes and lizards depend on external temperature and behaviour such as basking and burrowing to influence their body temperature and hence their metabolism. The temperature range at which a snake's/ lizard's metabolism functions most effectively is referred to as the preferred optimum temperature zone (POTZ). The POTZ may vary at different times of the year and even different times of the day.