Since its emergence two decades ago, the use of infrared technology for noninvasively measuring the heartbeat
rates of invertebrates has provided valuable insight into the physiology and ecology of intertidal organisms.
During that time period, the hardware needed for this method has been adapted to currently available electronic
components, making the original published description obsolete. This article reviews the history of heartbeat sensing
technology, and describes the design and function of a modern and simplified infrared heartbeat rate sensing
system compatible with many intertidal and marine invertebrates. This technique overcomes drawbacks and
obstacles encountered with previous methods of heartbeat rate measurement, and due to the sensor’s small size,
versatility, and noninvasive nature, it creates new possibilities for studies across a wide range of organismal type
