You searched for: “poikilothermic
poikilothermal, poikilothermic (adjective) (not comparable)
A reference to an animal that has a body temperature that fluctuates based on the temperature of the surrounding environment: exothermal; ectothermic; exothermic; heterothermic: Most animals, except mammals and birds, are considered to be poikilothermal or poikilothermic.