This book describes the methodology used to determine sterol content in coral reef food webs, and how sterol data is used in trophic ecology studies. The authors briefly explain the basics of gas chromatography and mass spectrometry as necessary tools to confidently separate, identify, and quantify sterols. Sterols from different sponge families have been described, however, few studies have been conducted involving the sterols of the freshwater sponge compared to those of the marine environment. The number of sterols present varies with the species, and this characteristic make it possible...