Nutrition and feeding preferences in the Caribbean echinoid Clypeaster rosaceus (Echinodermata: Echinoidea)  <B>Nutrition and feeding preferences in the Caribbean echinoid Clypeaster rosaceus (Echinodermata: Echinoidea)</B><P><B>Susanne Kampfer & Jörg Ott</B><I><P> University of Vienna, Institute of Zoology, Althanstraße 14, A-1090 Vienna, Austria</I><B><P> Abstract</B><BR> The irregular sea urchin <I>Clypeaster rosaceus</I> is believed to feed mainly on seagrass detritus. In contrast, specimens from shallow turtle grass meadows in the Belize Barrier Reef have been found to forage primarily on calcareous <I>Halimeda</I> debris although seagrass debris is the most abundant POM source. The urchins selectively ingest large-sized <I>Halimeda</I> particles, probably due to their high organic content and dense microbial colonization. Due to its preference for large particles which are ground to grain sizes <0.5 mm <I>C. rosaceus</I> plays an important role in bioerosion. Approximately 5.5 kg of coarse sediment is converted to silty fine sand by one individual per year.<I><P> Keywords</I>: bioerosion, echinoids, food selection, <I>Halimeda </I>spp<I>.</I>, <I>Thalassia testudinum.</I><P>