Optical, thermal, and structural characterization of the sclerotized skeleton of two antipatharian coral species

Optical, thermal and structural characterization of the skeleton of two black coral species from the Western Caribbean Sea, Antipathes caribbeana and Antipathes pennacea is presented. Optical spectra in the UV–VIS region of both species have a strong absorbance around 350 nm. FTIR spectra in the mid-infrared spectra show the presence of a complex material similar to chitin for both species. X-ray diffraction analyses demanded a deproteinization treatment in order to observe the significant differences in the crystalline structure of chitin. The crystallite size in A. caribbeana is larger than in A. pennacea. Thermal characterization, performed by the photoacoustic technique, shows that in A. caribbeana skeleton the thermal conductivity is higher as compared with the thermal conductivity of the skeleton of A. pennacea. The difference in the thermal properties between coral species could be due to the array and packing of the chitin fiber skeletons.