Figure 29.7: The Metabolic Rate of a Poikilotherm Slows Down as Temperature Decreases Jacqueline Litzgus and William Hopkins measured the standard metabolic rate of the mud turtle Kinosternon subrubrum at varying body temperatures.a They showed that temperature has a significant effect on standard metabolic rate in this species. The standard metabolic rate of a poikilotherm is its metabolic rate when resting and fasting. It can be measured at any body temperature of interest. (Poikilotherms do not have thermoneutral zones, explaining why the BMR concept does not apply to them.)