Chitinous materials are common in nature and provide different functions including protection and support of many invertebrate animals. Exoskeletons in these organisms constitute the boundary regulating interaction between the animal and the external environment. For this reason, it is important to study the physical properties of these skeletons, in particular, thermal properties. The objective of this study is to investigate the thermal diffusivity of the skeletons of four species of marine invertebrates, Antipathes caribbeana (black coral), Panulinus argus (lobster), Callinectes sapidus (crab), and Limulus polyphemus (xiphosure). Thermal characterization is performed using photothermal radiometry (PTR) and laser-flash techniques. The measurements are complemented with structural characterization using X-ray diffraction. The results using both laser flash and PTR are consistent. These indicate that the thermal properties are strongly dependent on the presence of biogenic minerals (calcium and/or magnesium) and on the crystallinity index of the structure. The thermal-diffusivity values show an increase as a function of the crystallinity index. © 2012 Springer Science+Business Media, LLC.