Thermomechanical and structural properties of two marine species exoskeletons, Antipathes caribbeana (black coral) and Limulus polyphemus (xiphosure), were studied using dynamic mechanical thermal analysis (DMTA), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). DMTA curves indicate the viscoelastic behavior and glass transition around 255 degrees C, black coral presented a second transition (175 degrees C) associated to the acetamide group attached to the alpha-chitin chain. DSC measurements showed a endothermic peak around 100 degrees C, with enthalpies of 4.02 and 118.04 J/g, indicating strong differences between exoskeletons respect to their water holding capacity and strength water polymer interaction. A comparative analysis involving DSC and X-ray diffraction showed that lower values Delta H in xiphosure correspond to a material with a higher crystallinity (30), in contrast black coral exhibits higher values Delta H and a lower crystallinity (19). FTIR confirmed alpha-chitin based structure, at higher temperature diminishes the amide bands and a new one appears, related to C-N groups. (C) 2015 Elsevier B.V. All rights reserved.