Changes in temperature, pH, or respiratory gases can dramatically affect heart function. Yet many ectothermic animals experience these environmental changes routinely as part of their day to day life. This talk will explore strategies of cardiac adaptation that permit maintenance of heart function in animals living in fluctuating environments. Interrelated aspects of ectotherm cardiac physiology will be discussed across levels of biological organization and across a variety of fish and reptile species. Excitation-contraction coupling during temperature change will be explored, in particular, the ‘mysterious’ role of the ectotherm sarcoplasmic reticulum. The talk will also consider mechanical regulation of ectotherm heart function and sarcomeric adaptations that allow extremes of stroke volume. The overall aim is to share my excitement for ectotherm cardiac physiology and highlight the growing importance of understanding the tolerances and adaptability of ectotherm hearts as our climate changes.