Sterols in coral-reef animals

The sterol constituents of both coral and non-coral-reef animals (mollusks, coelenterates, echinoderms) have been investigated, and determined by gas-liquid chromatography and spectral analyses. All coral-reef animals examined contained larger amounts of C₂₈-sterols, such as 24-methylcholesterol, than non-coral-reef animals. The seastar Acanthaster planci contains the same sterol constituents as some coral-reef coelenterates and mollusks, differing only in the position of the double bond in a steroid ring. This observation suggests the transport of dietary ⁵-sterols to ⁷-sterols through the food-chain in A. planci.