The brittle-stars Ophiocoma wendtii, O. echinata and O. pumila occur under rubble and in crevices in coral heads shoreward of the reef crest. To determine if the three species differed in use of resources, the sizes of crevice openings used were measured, feeding methods
and behavior were observed, and stomach contents examined. The three species were found to use crevices of different sizes, which in part may be a function of their difference in size: but size alone is unlikely to be the reason for the use of such large crevices by O. wendtii. All
three species were observed to suspension- and deposit-feed, but differed in the degree to which they exposed themselves, and in the feeding areas used in relation to their crevices. The analysis of stomach contents revealed a broad overlap in diet and particle size, but those of O. wendtii
had the highest amount of very fine flocculent material, and O. pumila, the smallest species, contained the largest particles. Thus these three closely related species, which appear to co-exist, when studied in detail show striking and subtle differences in several aspects of their
life habits. The availability of suitable sized crevices is likely to be a major determinant of the distribution of the species.
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