Mid-IR Imaging Can Detect Waste Heat Production in the Nematode Caenorhabditis elegans

Organisms carry out metabolic processes to produce chemical energy, but these biochemical pathways are inherently inefficient, resulting in the loss of energy as heat. This study reports the first characterization of the thermal signature of waste heat production in the ectothermic invertebrate Caenorhabditis elegans using thermal infrared (8-10 μm) imaging. A label-free imaging approach was developed to distinguish the heat output of living versus dead C. elegans by employing a cold object in reflectance mode with a highly reflective imaging substrate to suppress the thermal background. This method reveals a clear, repeatable difference in both the thermal output and cooling rate of living versus dead worms. Fourier Transform Infrared (FT-IR) spectroscopy confirms that the measured temperature differences arise from variations in kinetic temperature rather than differences in thermal emissivity. This novel approach provides a powerful tool for studying the previously inaccessible thermal biology of small ectothermic invertebrates.