This review emphasizes how ectothermic animals respond physiologically to environmental temperature changes and cold stress. Generally ectothermic animals cannot generate heat to maintain their body temperature but they can still survive in various temperature zones. Various organisms have been analyzed anatomically and physiologically in the attempt to understand the underlying mechanisms of this temperature adaptation. A few of the changes in the metabolic and molecular function of proteins are discussed. The potential of how hormonal modulation of cardiac and nervous systems which influences responses during exposure cold exposure is also addressed. The focus of this review is on the effect of cold exposure on synaptic transmission and cardiac function in crustaceans and insects.